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Articles 1 - 8 of 8
Full-Text Articles in Biogeochemistry
Quantifying Co2 And Ch4 Fluxes In A Semi-Arid Floodplain: Assessing Spatial And Temporal Drivers, Miles E. Kelsey
Quantifying Co2 And Ch4 Fluxes In A Semi-Arid Floodplain: Assessing Spatial And Temporal Drivers, Miles E. Kelsey
Earth and Planetary Sciences ETDs
Rivers transport sediment and carbon across Earth’s surface, and their floodplains can store carbon over decades to millennia, making them important to terrestrial carbon management. While soil carbon can persist long term, it may be released as greenhouse gases through processes like methanogenesis and heterotrophic respiration. Environmental controls on these fluxes remain poorly constrained across floodplains in different climate and geomorphic setting, but especially in semi-arid systems where measurements are limited. To address this gap, we quantified CO₂ and CH₄ fluxes along the Middle Rio Grande (New Mexico, USA) using 227 chamber measurements collected May to November 2025 at three …
Using Triple Oxygen Isotopes To Investigate Water Usage In Desert Ecosystems, Cloe V. Knutson
Using Triple Oxygen Isotopes To Investigate Water Usage In Desert Ecosystems, Cloe V. Knutson
Earth and Planetary Sciences ETDs
In arid environments, maintaining water balance can be more critical for survival than obtaining food. As droughts intensify, understanding how animals manage body water is essential. Triple oxygen isotope analysis provides a novel way to trace water sources in animals, distinguishing contributions from free water, food-derived oxygen, and atmospheric O2. We developed an equilibration method using CO2–H2O oxygen exchange and measured δ’18O and Δ’17O values via tunable infrared laser direct spectroscopy (TILDAS). Validated against traditional fluorination methods, this technique enables streamlined analysis of whole blood and plant samples. Applied to …
Petrographic And Geochemical Records Of Climate Perturbation In Carbonates From A Perennially Ice-Covered Antarctic Lake, Jared Clance
Petrographic And Geochemical Records Of Climate Perturbation In Carbonates From A Perennially Ice-Covered Antarctic Lake, Jared Clance
Earth and Planetary Sciences ETDs
Carbonate precipitation in perennially ice-covered Lake Fryxell, McMurdo Dry Valleys, Antarctica produces a modern analog for Antarctic paleolake carbonates. Lake Fryxell contains a steep oxycline in the photic zone, where dissolved oxygen falls from supersaturation to zero. In the lake’s benthic microbial mats, oxygen concentrations are higher than in the water column due to microbial photosynthesis. These mats contain carbonate cements that precipitated in a discrete episode from mat pore waters. Precipitation continued through seasonal fluctuations in oxygenation, demonstrated by variable concentrations of oxidized and reduced manganese and iron within carbonates. Carbonates precipitated out of isotopic equilibrium with the lake …
Effects Of Environmental Change On Ancestral Pueblo Fishing In The Middle Rio Grande, Jonathan William Dombrosky
Effects Of Environmental Change On Ancestral Pueblo Fishing In The Middle Rio Grande, Jonathan William Dombrosky
Anthropology ETDs
It has long been assumed that fishes were unimportant in the diet of past Pueblo people in the U.S. Southwest. Yet, small numbers of fish remains are consistently recovered from Late pre-Hispanic/Early Historic archaeological sites in the Middle Rio Grande of New Mexico. The end of drought conditions may have impacted food choice and fishing decisions during this time. I use behavioral ecology to understand how fishing could have been an optimal food-getting strategy for Ancestral Pueblo farmers. Stable isotope analysis offers a way to account for environmental change. I provide a refined 13C Suess correction model to support …
Reconstructing Energy Flow Through Modern And Historical Marine Communities: Insights From Amino Acid Isotope Analysis, Emma A. Elliott Smith
Reconstructing Energy Flow Through Modern And Historical Marine Communities: Insights From Amino Acid Isotope Analysis, Emma A. Elliott Smith
Biology ETDs
The fundamental currency of life is energy. Organisms need energy to grow, to survive and to reproduce. Understanding the acquisition of energy by consumers is thus a foundational aspect of biological research. This is especially important in the modern era, as impacts of ongoing anthropogenic effects will be mediated or amplified through food webs. Here, I explore how isotopic analysis of individual amino acids – a technique new to ecological studies – can be used to trace energy flow through animal communities in modern and ancient time periods. In particular, I focus on kelp forest food webs, which are nearshore …
Carbon And Nitrogen Stable Isotopes In Organic Matter From Lake Chalco, Mexico: A Record Of Quaternary Hydrology And Climate Change, Kristin Slezak Pearthree
Carbon And Nitrogen Stable Isotopes In Organic Matter From Lake Chalco, Mexico: A Record Of Quaternary Hydrology And Climate Change, Kristin Slezak Pearthree
Earth and Planetary Sciences ETDs
Sediment cores from Lake Chalco, central Mexico, were analyzed to reconstruct paleoclimate in the neotropics. This study employs total organic carbon, organic carbon-organic nitrogen ratios, carbon and nitrogen stable isotope ratios of organic matter (OM), and lithology to reconstruct changes in lake level and productivity. During Marine Isotope Stage 3 (~42-29 ka) bulk OM d13C and d15N results suggest the lake experienced strong evaporation and high pH due to warm temperatures and moderate precipitation. Large amounts of terrestrial C3 plant matter were deposited during the Last Glacial Maximum (~22-19 ka), suggesting a swampy environment resulting from …
Are The Oxygen Isotope Values Of The Late Cretaceous Western Interior Seaway Different From The Open Ocean?, Camille H. Dwyer, Corinne Myers, Viorel Atudorei
Are The Oxygen Isotope Values Of The Late Cretaceous Western Interior Seaway Different From The Open Ocean?, Camille H. Dwyer, Corinne Myers, Viorel Atudorei
Shared Knowledge Conference
The Western Interior Seaway (WIS) was a North American epicontinental sea that was connected to the open ocean through the passage of the northern Boreal Sea and the southern Tethys Sea from the early Albian (~113 million years ago) to the early Paleogene (~65 million years ago). The WIS began to recced and lost its connection to the southern Tethys Sea in the late Campanian (~72 million years ago). In the early Paleogene, the WIS dried up completely. The oxygen isotopic composition (δ18O) of benthic bivalves was measured from the upper Campanian and lower Maastrichtian (75 million years ago to …
Mainland Southeast Asia In The Longue Durée: A Zooarchaeological Test Of The "Broad Spectrum Revolution" In Northern Thailand, Cyler Norman Conrad
Mainland Southeast Asia In The Longue Durée: A Zooarchaeological Test Of The "Broad Spectrum Revolution" In Northern Thailand, Cyler Norman Conrad
Anthropology ETDs
In northern Thailand, previous zooarchaeological research suggests that hunter-gatherers consumed a broad diversity of animal resources during the Pleistocene-Holocene transition and afterwards (Gorman 1971a). This is a pattern characteristic of Kent Flannery’s (1969) “broad spectrum revolution” hypothesis. Based primarily on presence and absence evidence, faunal assemblages in northern Thailand typically include species of mammals, reptiles, birds, fish and shellfish, suggesting that prehistoric foragers consumed a wide range of taxa within this mainland Southeast Asian tropical environment. Although zooarchaeological analyses commonly identify this pattern within prehistoric cave and rockshelter sites, past investigations have 1) not attempted to formally test Flannery’s hypothesis, …