Professor Gabriel Bowen
Purdue University - Department of Earth & Atmospheric Sciences
Earth & Atmospheric Sciences
550 Stadium Mall Drive
Purdue University
West Lafayette, IN 47907
Phone: 765.494.3258
Fax: 765.496.1210
Projects
A new feedback on the carbon cycle involving clays and the hydrologic cycle: Stabilization of climate during the Paleocene-Eocene thermal maximum (supported by ACS/PRF, 7/1/06 - 8/31/08).
Human alteration of the carbon cycle is one of the best documented direct effects of societal and technological development on natural Earth Systems. This change has the potential to affect climatic, biological, and human systems, impacting the character and habitability of the world we live in. As a result, it is critical that scientists pursue a complete, mechanistic understanding of the carbon cycle, and in particular of its capacity to adapt to and recover from dramatic perturbation. We are exploring a potential feedback mechanism through which soil carbon (a large, dynamic and poorly understood carbon reservoir) may counteract increases in atmospheric carbon concentrations. Our hypothesis is that increased intensity of the hydrological cycle, which is predicted by most climate models in a warmer, CO 2 greenhouse world, leads to increased sequestration of soil-derived organic carbon through accelerated of clay mineral formation in soils, enhanced stabilization of soil organic carbon through adsorption to clay mineral surfaces, and elevated rates of clay-associated organic carbon export and burial on the marine shelves. We are testing the hypothesis by studying the geological record of the Paleocene-Eocene thermal maximum (PETM), a well-studied, elevated-CO 2 global greenhouse event that we will use as an analogue to modern global warming. We are working to reconstruct rates of accumulation and sources of clay-associated organic carbon in terrestrial and marginal marine rocks through the PETM, identifying and quantifying changes in this carbon burial flux associated with PETM climate change.
The Lake Flagstaff system as a barometer for hydroclimatological and ecological change during the Paleocene-Eocene thermal maximum.
Abrupt climatic warming, carbon cycle perturbation, and ecological change during the Paleocene-Eocene thermal maximum (PETM, ~55 million years ago) has now been documented at sites worldwide. This event has received study both as a pivotal event in the evolutionary history of many biological guilds and as a potential analogue for modern, anthropogenic carbon-induced global warming.
The IREH group, in collaboration with researchers at Northwestern and Idaho State Universities , is working to generate new records of the PETM from lacustrine and floodplain sedimentary rocks deposited within the Lake Flagstaff paleo-basin of central Utah . The lacustrine carbonates of the Flagstaff Formation and inter-tonguing, pedogenically modified clastic deposits of the North Horn Formation form a ~250 m thick package of latest Paleocene to earliest Eocene rocks exposed on topographic plateaus throughout much of central Utah. Previous work by Prof. Bowen in this region has 1) verified that primary geochemical information is preserved within Flagstaff limestones, and 2) provided evidence that the prominent, negative carbon isotope excursion marking the PETM within North Horn Formation paleosol carbonates. Ongoing research is focused on confirming and extending the correlation of the PETM within the North Horn and Flagstaff Formations through field studies and stable isotope stratigraphy of mineral, bulk organic, and biomarker substrates. We are seeking support to extend this project and 1) develop reconstructions of changes in regional hydroclimatology (most critically precipitation/evaporation ratios) through sedimentological and geochemical study of the Flagstaff Fm., and 2) explore the Flagstaff paleo-basin as a source of paleobiological information through focused study of invertebrate and ichno-fossils and exploratory work to identify vertebrate and plant fossil preservation in the region.
Photo caption: Sunset on the Flagstaff Formation, Wasatch Plateau, central Utah
Dynamics of carbon release and sequestration: Case studies of two early Eocene hyperthermals (supported by NSF, 9/15/06 - 8/31/09)
The Earth's climate was restless during the early part of the Eocene epoch. During several dramatic twitches, global temperatures warmed dramatically and then settled back to normal levels after 100 thousand years or more. Carbon isotope ratio data and records of carbonate preservation on the ancient seafloor tell us that each twitch was accompanied by abrupt increases in the level of carbon dioxide in the atmosphere and oceans. This carbon, derived from organic carbon buried in sediments or rocks, was released to the atmosphere and oceans and perturbed global climate for many thousands of years, then gradually stripped away and re-buried in rocks. Sound familiar?
In this project the IREH group is collaborating as a part of a team of 9 scientist at 8 US universities and several foreign collaborators to better understand how and why this carbon was released, how it affected Earth's climate and ecosystems, and how it was ultimately returned to the subsurface. The project will involve both generation of new datasets documenting the characteristics of these 'hyperthermal' events and detailed modeling studies to understand the impacts and feedbacks associated with carbon release. The primary contribution of the IREH group will be in developing models of terrestrial ecosystem, soil, and hydrological processes and applying them to study the role of the continents in stabilizing the carbon cycle and climate during these events. This project will interface with other ongoing IREH projects that will provide new datasets against which model scenarios can be tested.
Holocene water balance of the northeastern Great Basin (supported by NSF, 9/15/06 - 8/31/10)
In many parts of the world, water is a limiting resource for plants, animals, and humans. For arid regions such as the southwestern United states , understanding variability in the availability of water is critical to forecasting and planning for the risks associated with population growth and urban development. This understanding must include an understanding of natural levels of variability in water balance (precipitation - evaporation). The IREH group is working to generate records documenting the last ~8,000 years of water cycle history as recorded in the sediments of the Great Salt Lake . This time interval includes several well-documented warm- and cool-climate intervals, allowing us to investigate the response of the water cycle to climate change. The records, based on the isotope geochemistry of organic biomarkers, will let us probe the Holocene water cycle of this arid part of the western U.S. for prolonged intervals of dry and wet climate, and improve our understanding of when and why these intervals occurred. As a component of the project, we are also calibrating new proxies for water cycle reconstruction based on the organic fossils of brine shrimp.
Natural abundance H and O isotopes for forensic science, ecology, and hydrology.
The IREH group is continuing to work in collaboration with a number of colleagues to develop GIS-based models and tools supporting applications of environmental H and O isotope variation to a range of basic and applied science fields. This work began with our research into geostatistical models predicting the spatial distribution of these isotopes in rainwater (see www.waterisotopes.org for a description of this work). Ongoing efforts include the development of mechanistic models that can be applied over large spatial scales to predict isotope ratios in other components of the hydrological cycle and integration of data from spatial data networks with models to study hydrological processes at the catchment to continental scales. In addition to improving our understanding of water resource connectivity and stability, this research will produce products for use in reconstructing the origin of forensic samples and probing ecological systems.
Figure caption: Modeled river water hydrogen isotope ratios in northern New Mexico (unpublished)
The Isotope Networks Portal: Data Integration for Biogeochemistry and Ecology Through Web-based Geospatial Modeling.
A new organizational model for data-driven science is emerging and may support generation of large data sets for environmental and ecological parameters at numerous sites across the U.S. , perhaps the globe. These data will provide uniformity in measurement types and methods and public data availability, enabling unique research opportunities through providing data for simultaneous study of equivalent systems at numerous spatially distributed sites. A primary challenge facing scientific consumers of this data is that no common framework exists for accessing and integrating this data with a diverse array of other data sources and models needed to apply the data to biological research questions. The IREH group is developing a collaborative effort to produce a web-based GIS portal, INPort (Isotope Networks Portal), that will provide a transparent interface between data consumers and data sources via integrated data querying, data acquisition, and geospatial modeling operations. Users will interact with INPort through a map-based interface that will allow spatiotemporal domain and model selection and parameter specification. INPort software will conduct data identification, acquisition, and processing and model execution behind the scenes while allowing the user to monitor the project status. Model output and documentation will be provided as live, interactive GIS data layers for display and manipulation within INPort or user download. In total, INPort will provide a seamless environment for integrated data/model exploration, visualization, and hypothesis testing.
