Andrew J. Frierdich ($2,500)
Ph. D. Student
Department of Earth and Planetary Sciences
Washington University in St. Louis
Geochemistry of Ferromanganese Deposits in Pautler Cave, Southwestern Illinois Karst:
Formation, Structure, and Influence on Trace Element Transport and Sequestration
Abstract - Nano-crystalline iron (Fe) and manganese (Mn) oxides are ubiquitous in caves, and play a major role in controlling the fate and transport of numerous potentially toxic trace elements in karst aquifers. However, little is understood about the biogeochemical processes controlling the dissolution, transport, and precipitation of these minerals in karst systems or the mechanisms by which they sequester trace elements. Recent results indicate that Mn oxide coatings from cave stream pebbles, collected from caves in the southwestern Illinois karst, contain anomalously high concentrations of uranium (U). This discovery is interesting from an environmental point of view, but it also provides an opportunity to develop a unique U-series method for dating these coatings. Such a method could provide information about the time scales in which cave stream incision occurs if coated pebbles can be collected from various levels within a cave (e.g., in the present cave steam, in old upper dry passages). The objective of this study is to investigate the aqueous geochemical parameters controlling the source, transport, and formation of Fe and Mn oxide minerals in limestone caves. Solid samples will be thoroughly characterized with numerous instrumental techniques. Geochemical modeling of the redox chemistry of the cave water will be used to explain the spatial distribution of Fe and Mn, and the energetics of possible microbial metabolic pathways responsible for Fe and Mn oxidation. In addition, the concentration and speciation of U in these deposits will be determined, which may provide necessary preliminary data to develop a geochronological method.
Logan Kistler ($1,500)
Ph. D. Student
Department of Anthropology
Pennsylvania State University
Ancient Plant DNA Analysis of the Prehistoric Eastern Chenopod
Abstract- Previous research has revealed the importance of several crop plants cultivated in eastern North America beginning by about 5,000 calendar years before the present. Assemblages of archaeobotanical material from dry caves and rockshelters have been central to archaeologists' understanding of prehistoric subsistence in the area, including the importance of these domesticated plants during the Late Archaic and Early Woodland Periods. Although the importance of pre-maize agriculture is well established, it remains unclear where the cultivated plants were initially brought under domestication by humans. This study will use DNA analysis of modern and archaeological materials to better understand the origin of chenopod (Chenopodium berlandieri Moq.), one of the domesticated plants occurring frequently in caves and other archaeological sites in the Eastern Woodlands. Two competing hypotheses exist regarding the location of chenopod domestication. The eastern origin hypothesis suggests that chenopod was domesticated from a native species in the Eastern Woodlands, supporting eastern North America's status as an independent center of agricultural origin. Proponents of the competing Mesoamerican origin hypothesis argue that the prehistoric eastern chenopod was derived from a Mexican variety that is still cultivated as a field crop today, and that was introduced to the Eastern Woodlands in prehistory. Comparison of ancient DNA sequence data with a diverse sample of modern wild and cultivated chenopods will allow the identification of the prehistoric chenopod's site of domestication.
Katherine Knierim ($2,000)
Department of Geology
University of Arkansas
The Use of Nitrogen and Carbon Stable Isotopes to Monitor Denitrification in the Karst Terrain of Northwestern Arkansas
Abstract - Nitrate contamination in karst environments has the potential to negatively impact water quality because of the decreased purification capacity of karst rocks (Panno et al., 2001). Northwestern Arkansas is characterized by karst landscape and a large agriculture industry, which contributes to nitrate pollution of groundwater (Peterson et al., 2002). Denitrification is an important mechanism for removal of nitrate, but nutrient processing in karst landscapes is poorly understood (Peterson et al., 2002; Winston, 2003). To better quantify nutrient processing, the stable isotopic compositions of nitrate and nitrogen gas (?15N, ?18O) and organic/inorganic carbon and gaseous carbon dioxide (?13C) will be monitored in a karst setting in northwestern Arkansas. To test the hypothesis that changes in these isotopic compositions of carbon and nitrate can be used to monitor denitrification, compounds labeled with heavy nitrogen and carbon isotopes will be added to the hydrologic system and measured along the groundwater flow path, from the soil, to a cave, to discharge at springs. This experiment will provide insight into how nutrients are processed in karst settings and, specifically, how cave environments are impacted by agricultural pollution.
Peter J. van Hengstum ($2,500)
Department of Earth Sciences
Dalhousie University, Canada
Developing a Combined Micropaleontological (Foraminifera) and Stable Light Isotopic (δ13C, δ18O) Approach for Reconstructing Flooded (Phreatic) Coastal Caves
Abstract - Flooded (phreatic) coastal cave systems have a global distribution, provide an observation site for continental-oceanic subterranean circulation, host unique and endangered aquatic ecosystems, provided a refuge for early-Holocene hunter-gather human populations, are structurally and environmentally influenced through sea level change, and are currently threatened by groundwater pollution from coastal urbanization. Despite their inter-disciplinary importance, there is currently no developed proxy capable of monitoring or evaluating environmental evolution in phreatic caves-a significant research problem. Foraminifera have a wide reputation as coastal proxies, where researchers can apply paleoecology and the isotopic geochemical signals preserved in foraminifer shells (i.e., carbon, oxygen) to reconstruct various environmental parameters (sea level change, salinity, organic matter fluxes, etc.). However, foraminiferal ecology and their paleoenvironmental utility have yet to be systematically evaluated in coastal phreatic caves. Based on multiple lines of global evidence, foraminifera are systematically colonizing phreatic caves and can address the problem. The goal of this research is to develop foraminifera as environmental proxies in phreatic coastal caves by (1) examining their modern ecology and isotopic geochemistry in caves, and (2) evaluating their long-term utility as proxies by investigating historical foraminifer distributions in phreatic cave sediments. This research is anticipated to: (A) provide basic ecological information of foraminifera in phreatic caves, (B) evaluate foraminifera as environmental proxies in phreatic caves, and (C) develop a multi-proxy (paleoecology and geochemistry) and interdisciplinary (earth, biological, and chemical sciences) approach for reconstructing long-term environmental changes (sea level oscillations, climatic shifts, hydrogeological changes, etc.) archived in global coastal caves.