REU Research Projects

REU Projects

At the University of Arizona, we are building a program to bridge the gap between laboratory- and field-scale studies by utilizing the unique infrastructure of Biosphere 2. Biosphere 2 offers unique opportunities for the exploration of complex questions in Earth sciences because of its ability to combine varying scales, precise manipulation and fine monitoring in controlled experiments. By building upon the large external scientific network at the University of Arizona in hydrology, geology, geochemistry, ecology, biology, physics, engineering and atmospheric sciences, we are developing a strong multidisciplinary team of researchers who are undertaking the design and deployment of top-notch science to address complex questions in environmental sciences. Projects for 2022 REU students include:


Ecosystem Science, Renewable Energy Production, Food, and Water Sustainability

Greg Barron-Gafford, Department of Geography and Development, and Biosphere 2. External forces (like environmental and human factors) and internal characteristics (like plant ecophysiology) determine where species can live and thrive. This nexus is critical for tackling one of the greatest challenges facing our future - how to simultaneously maximize renewable energy production and food production without degrading the environment. The "Agrivoltaics" installation at B2 blends renewable energy production from solar photovoltaics with agriculture to study the impacts of this novel approach on plant function, water use, and biomass production.


Students in the Tropical Rain Forest
Tropical Forest Dynamics and Trace Gas Fluxes

Joost van Haren, Biosphere 2. Tropical forests are among the most dynamic ecosystems in the world, but their responses to climate change are uncertain. B2 provides an opportunity to study tropical ecosystems under future conditions (increased temperature, decreased precipitation); the large enclosure and artificial rainfall allows precise determination of water and carbon movement through the biome. Students use the B2 tropical forest to assess plant, hydrological, and carbon cycling responses to altered temperature and precipitation.




Student working in the soil pit of rain forest


Microbes as the engineers of the soil, plants, and atmosphere

 Laura Meredith, SNRE. How do soil microbiomes affect the biosphere, and specifically, its atmosphere? Our research focuses on interactions between ecosystems and the atmosphere that affect climate, air quality, and ecosystem health. I study the role of soil microbiomes in ecosystems and their immense capacity to transform matter in ways that release, or take up, trace gases. My group measures microbial cycling of trace gases that influence climate (e.g., nitrous oxide, methane, carbon dioxide) and mediate biological interactions belowground (e.g., volatile organic compounds). Our research aims to measure and decode new microbial signals in the soil in the Biosphere 2 Tropical Rainforest and the Landscape Evolution Observatory. The student(s) involved in this project will have the opportunity to learn methods in microbial genomics, bioinformatics, and analytical atmospheric chemistry by contributing to ongoing research campaigns and data analysis.




Student swimming in Biosphere 2 Ocean


Calcification & biomineralization under a changing climate

 Diane Thompson, Department of Geosciences (GEOS). The Biosphere 2 Ocean (B2O) mesocosm provides a unique opportunity to isolate the impacts of temperature and acidification on calcifying reef organisms at ecosystem scale.  Leveraging this scale and control, this project will assess the impact of changing ocean conditions on the growth of calcifying reef organisms, and in turn, the climate records generated from carbonate skeletons (e.g., corals, coralline algae, bivalves, and foraminifera). Controlled experimental studies are required to understand the processes by which geochemical signals are incorporated into the carbonate skeleton during the calcification process (“biomineralization”), and how these processes change as a function of calcification rate, species and environmental conditions. This project will provide REU students with hand-on research experience at the interface of reef ecology, geochemistry, and paleoclimatology in the largest experimental ocean facility in the world, working with leading paleoclimate researchers in GEOS.



Biological weathering in the Critical Zone

Jon Chorover, Department of Environmental Science (ENVS). Chorover’s lab provides opportunities to investigate (bio)geochemical aspects of critical zone evolution, including work at two potential sites within the UA-led Catalina Mountains (AZ) and Jemez River Basin (NM). Students would couple field work and laboratory studies to understand subsurface biogeochemical processes, including the effects of plants and microbes on the rate and trajectory of rock transformation to soil.



Deep groundwater resources: quantity, quality and competition for limited supplies

Jennifer McIntosh, Department of Hydrology and Atmospheric Sciences. In the southwestern US and around the world, people are increasingly turning to groundwater to meet water resource demands and large regions of significant groundwater depletion have been documented from space. Yet, the quantity and quality of groundwater resources at depth, and their connection to the near-surface water cycle, are uncertain. In addition, deep groundwater resources are potentially impacted by energy production (e.g., oil and gas wells) and storage of energy-related waste products. Students will use existing datasets of groundwater chemistry and apparent ages in relation to well depths and geologic information to assess controls on the depth of fresh and brackish groundwater resources, and do local fieldwork to collect water quality data.




Mineral weathering, soil formation and carbon sequestration as influenced by water flow and biota

 Katerina Dontsova, ENVS and B2. Projects at Biosphere 2 would focus on soil formation processes and development of subsurface heterogeneity through hydrologic-geochemical coupling using direct measurement and geochemical modelling: what happens in the basalt covering LEO slopes as a result of water flow and biological activity; what is the role of slope position, water residence time, and microbial activity on total weathering, chemical denudation, formation of high surface-area secondary solids, and accumulation of organic and inorganic carbon.





Landscape evolution and soil formation

 Craig Rasmussen, ENVS. Climate change over the Quaternary period (the last 2.58 million years) and associated cycles of erosion, sediment deposition, and soil formation have emerged as key modulators of modern day biogeochemistry and ecosystem function. In particular, CO2 consumption associated with mineral weathering and the interaction of this process with pedogenesis and erosion appear to be significant factors controlling long-term patterns in atmospheric CO2 concentration. Weathering and mass flux are hypothesized to vary predictably with landscape position, age, and climate forcing. This project aims to couple variation in soil development, mineral weathering, and surficial geomorphology across a range of arid and semiarid landscapes using field sampling, laboratory analyses, and data synthesis.





Hotter Earth system effects on the land surface

 David Breshears, School of Natural Resources and Environment (SNRE). The overall theme of the research for this project will related to the effects of warmer temperatures, both chronic and acute, on land surface characteristics such as soil moisture and associated changes such as vegetation die-off. The effects of heat waves will be an area of particular focus. Approaches may include revaluating historical events in the context of heat wave conditions, not just chronic warming; hydrological modeling of soil moisture dynamics under chronic and acute warming; and evaluation of microclimate change associated with vegetation die-off. Data and literature synthesis will also be applied to link land surface responses to chronic and acute warming effects during drought.




Geomorphology and land use dynamics of drylands

 Jason Field, SNRE.  Drylands are dynamic in response to aeolian (wind-drive) and fluvial (water-driven) processes. These processes include soil erosion affecting local geomorphology, dust production impacting air quality and local and sometimes distant climate, and soil-litter mixing affecting soil biogeochemical processes, particularly decomposition. Approaches may include field testing of aeolian and fluvial processes, modeling of contrasting scenarios, synthesis of existing data to update an existing framework on aeolian and/or fluvial processes, and/or interactions with land cover pattern and change, including management options for manipulating land surface properties and geomorphological processes. Drylands will be evaluated in the context of surface roughness as well as cover types (e.g. shrub, grass, biocrust, bare).




Microbial-organic matter interactions and controls in dynamically changing systems

 Malak Tfaily, ENVS. My research interests revolve around terrestrial interactions of geochemical and biological processes, at multiple scales (pore-to-ecosystem scale) and the resulting impact on the whole ecosystem. We use a combination of modern analytical molecular (high resolution mass spectrometry, etc.), geochemical (wet chemistry and gas flux), and isotopic techniques (natural abundance, and isotope enrichment) to answer where and how organic matter degradation and formation takes place in different ecosystems. Students would couple field work and laboratory studies to understand and examine the direct relationship between organic matter composition, the activity of the biological community, the geochemical signature of the activity and how that signature may translate between environments.