Matching Items (5)
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- All Subjects: Hydrothermal
- All Subjects: carbon cycling
- Creators: Hartnett, Hilairy
- Creators: Childers, Daniel
Description
Dissolved organic matter (DOM) can have numerous effects on the water chemistry and the biological life within an aquatic system with its wide variety of chemical structures and properties. The composition of the dissolved carbon can be estimated by utilizing the fluorescent properties of some DOM such as aromatic amino acids and humic material. This experiment was used to observe how organic matter could influence hydrothermal systems, such as Sylvan Springs in Yellowstone National Park, USA. Using optical density at 600 nm (OD 600), excitation-emission matrix spectra (EEMS), and Illumina sequencing methods (16S rRNA gene sequencing), changes in dissolved organic matter (DOM) were observed based on long term incubation at 84ºC and microbial influence. Four media conditions were tested over a two-month duration to assess these changes: inoculated pine needle media, uninoculated pine needle media, inoculated yeast extract media, and uninoculated yeast extract media. The inoculated samples contained microbes from a fluid and sediment sample of Sylvan Spring collected July 23, 2018. Absorbance indicated that media containing pine needle broth poorly support life, whereas media containing yeast extract revealed a positive increase in growth. Excitation-Emission Matrix Spectra of the all media conditions indicated changes in DOM composition throughout the trial. There were limited differences between the inoculated and uninoculated samples suggesting that the DOM composition change in this study was dominated by the two-month incubation at 84ºC more than biotic processes. Sequencing performed on a sediment sample collected from Sylvan Spring indicated five main order of prokaryotic phyla: Aquificales, Desulfurococcales, Thermoproteales, Thermodesulfobacteriales, and Crenarchaeota. These organisms are not regarded as heterotrophic microbes, so the lack of significant biotic changes in DOM could be a result of these microorganisms not being able to utilize these enrichments as their main metabolic energy supply.
ContributorsKnott, Nicholas Joseph (Author) / Shock, Everett (Thesis director) / Hartnett, Hilairy (Committee member) / Till, Christy (Committee member) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Under current climate conditions northern peatlands mostly act as C sinks; however, changes in climate and environmental conditions, can change the soil carbon decomposition cascade, thus altering the sink status. Here I studied one of the most abundant northern peatland types, poor fen, situated along a climate gradient from tundra (Daring Lake, Canada) to boreal forest (Lutose, Canada) to temperate broadleaf and mixed forest (Bog Lake, MN and Chicago Bog, NY) biomes to assess patterns of microbial abundance across the climate gradient. Principal component regression analysis of the microbial community and environmental variables determined that mean annual temperature (MAT) (r2=0.85), mean annual precipitation (MAP) (r2=0.88), and soil temperature (r2=0.77), were the top significant drivers of microbial community composition (p < 0.001). Niche breadth analysis revealed the relative abundance of Intrasporangiaceae, Methanobacteriaceae and Candidatus Methanoflorentaceae fam. nov. to increase when MAT and MAP decrease. The same analysis showed Spirochaetaceae, Methanosaetaceae and Methanoregulaceae to increase in relative abundance when MAP, soil temperature and MAT increased, respectively. These findings indicated that climate variables were the strongest predictors of microbial community composition and that certain taxa, especially methanogenic families demonstrate distinct patterns across the climate gradient. To evaluate microbial production of methanogenic substrates, I carried out High Resolution-DNA-Stable Isotope Probing (HR-DNA-SIP) to evaluate the active portion of the community’s intermediary ecosystem metabolic processes. HR-DNA-SIP revealed several challenges in efficiency of labelling and statistical identification of responders, however families like Veillonellaceae, Magnetospirillaceae, Acidobacteriaceae 1, were found ubiquitously active in glucose amended incubations. Differences in metabolic byproducts from glucose amendments show distinct patterns in acetate and propionate accumulation across sites. Families like Spirochaetaceae and Sphingomonadaceae were only found to be active in select sites of propionate amended incubations. By-product analysis from propionate incubations indicate that the northernmost sites were acetate-accumulating communities.
These results indicate that microbial communities found in poor fen northern peatlands are strongly influenced by climate variables predicted to change under current climate scenarios. I have identified patterns of relative abundance and activity of select microbial taxa, indicating the potential for climate variables to influence the metabolic pathway in which carbon moves through peatland systems.
ContributorsSarno, Analissa Flores (Author) / Cadillo-Quiroz, Hinsby (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Childers, Daniel (Committee member) / Arizona State University (Publisher)
Created2022
Description
Dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) are crucial nutrients for autotrophic and heterotrophic microbial life, respectively, in hydrothermal systems. Biogeochemical processes that control amounts of DIC and DOC in Yellowstone hot springs can be investigated by measuring carbon abundances and respective isotopic values. A decade and a half of field work in 10 regions within Yellowstone National Park and subsequent geochemical lab analyses reveal that sulfate-dominant acidic regions have high DOC (Up to 57 ppm C) and lower DIC (up to 50 ppm C) compared to neutral-chloride regions with low DOC (< 2 ppm C) and higher DIC (up to 100 ppm C). Abundances and isotopic data suggest that sedimentary rock erosion by acidic hydrothermal fluids, fresh snow-derived meteoric water, and exogenous carbon input allowed by local topography may affect DOC levels. Evaluating the isotopic compositions of DIC and DOC in hydrothermal fluids gives insight on the geology and microbial life in the subsurface between different regions. DIC δ13C values range from -4‰ to +5‰ at pH 5-9 and from -10‰ to +3‰ at pH 2-5 with several springs lower than -10‰. DOC δ13C values parkwide range from -10‰ to -30‰. Within this range, neutral-chloride regions in the Lower Geyser Basin have lighter isotopes than sulfate-dominant acidic regions. In hot springs with elevated levels of DOC, the range only varies between -20‰ and -26‰ which may be caused by local exogenous organic matter runoff. Combining other geochemical measurements, such as differences in chloride and sulfate concentrations, demonstrates that some regions contain mixtures of multiple fluids moving through the complex hydrological system in the subsurface. The mixing of these fluids may account for increased levels of DOC in meteoric sulfate-dominant acidic regions. Ultimately, the foundational values of dissolved carbon and their isotopic composition is provided in a parkwide study, so results can be combined with future studies that apply different sequencing analyses to understand specific biogeochemical cycling and microbial communities that occur in individual hot springs.
ContributorsBarnes, Tanner (Author) / Shock, Everett (Thesis advisor) / Meyer-Dombard, D'Arcy (Committee member) / Hartnett, Hilairy (Committee member) / Arizona State University (Publisher)
Created2023
Description
Dissolved organic matter (DOM) is an important part of aquatic foodwebs because it contains carbon, nitrogen, and other elements required by heterotrophic organisms. It has many sources that determine its molecular composition, nutrient content, and biological lability and in turn, influence whether it is retained and processed in the stream reach or exported downstream. I examined the composition of DOM from vascular wetland plants, filamentous algae, and riparian tree leaf litter in Sonoran Desert streams and its decomposition by stream microbes. I used a combination of field observations, in-situ experiments, and a manipulative laboratory incubation to test (1) how dominant primary producers influence DOM chemical composition and ecosystem metabolism at the reach scale and (2) how DOM composition and nitrogen (N) content control microbial decomposition and stream uptake of DOM. I found that differences in streamwater DOM composition between two distinct reaches of Sycamore Creek did not affect in-situ stream respiration and gross primary production rates. Stream sediment microbial respiration rates did not differ significantly when incubated in the laboratory with DOM from wetland plants, algae, and leaf litter, thus all sources were similarly labile. However, whole-stream uptake of DOM increased from leaf to algal to wetland plant leachate. Desert streams have the potential to process DOM from leaf, wetland, and algal sources, though algal and wetland DOM, due to their more labile composition, can be more readily retained and mineralized.
ContributorsKemmitt, Kathrine (Author) / Grimm, Nancy (Thesis advisor) / Hartnett, Hilairy (Committee member) / Throop, Heather (Committee member) / Arizona State University (Publisher)
Created2018
Hydrothermal reactions of organic compounds in the presence of minerals: a study of carboxylic acids
Description
Carboxylic acids are an abundant and reactive species present throughout our solar system. The reactions of carboxylic acids can shape the organic abundances within oil field brines, carbonaceous chondrites, and different ranks of coal.
I have performed hydrothermal experiments with model aromatic carboxylic acids in the presences of different oxide minerals to investigate the reactions available to carboxylic acids in the presence of mineral surfaces. By performing experiments containing one organic compound and one mineral surface, I can begin to unravel the different reactions that can occur in the presence of different minerals.
I performed experiments with phenylacetic acid (PAA), hydrocinnamic acid (HCA) and benzoic acid (BA) in the presence of spinel (MgAl2O4), magnetite (Fe3O4), hematite (Fe2O3), and corundum (Al2O3). The focus of this work was metal oxide minerals, with and without transition metal atoms, and with different crystal structures. I found that all four oxide minerals facilitated ketonic decarboxylation reactions of carboxylic acids to form ketone structures. The two minerals containing transition metals (magnetite and hematite) also opened a reaction path involving electrochemical oxidation of one carboxylic acid, PAA, to the shorter chain version of a second carboxylic acid, BA, in experiments starting with PAA. Fundamental studies like these can help to shape our knowledge of the breadth of organic reactions that are possible in geologic systems and the mechanisms of those reactions.
I have performed hydrothermal experiments with model aromatic carboxylic acids in the presences of different oxide minerals to investigate the reactions available to carboxylic acids in the presence of mineral surfaces. By performing experiments containing one organic compound and one mineral surface, I can begin to unravel the different reactions that can occur in the presence of different minerals.
I performed experiments with phenylacetic acid (PAA), hydrocinnamic acid (HCA) and benzoic acid (BA) in the presence of spinel (MgAl2O4), magnetite (Fe3O4), hematite (Fe2O3), and corundum (Al2O3). The focus of this work was metal oxide minerals, with and without transition metal atoms, and with different crystal structures. I found that all four oxide minerals facilitated ketonic decarboxylation reactions of carboxylic acids to form ketone structures. The two minerals containing transition metals (magnetite and hematite) also opened a reaction path involving electrochemical oxidation of one carboxylic acid, PAA, to the shorter chain version of a second carboxylic acid, BA, in experiments starting with PAA. Fundamental studies like these can help to shape our knowledge of the breadth of organic reactions that are possible in geologic systems and the mechanisms of those reactions.
ContributorsJohnson, Kristin Nicole (Author) / Shock, Everett (Thesis advisor) / Hartnett, Hilairy (Committee member) / Gould, Ian (Committee member) / Arizona State University (Publisher)
Created2017