Land and Fresh Water
Microbiology and Ecology
Microorganisms are drivers of global biogeochemical cycles and represent the most abundant and diverse forms of life on Earth. Critical biological transformation processes such as nitrogen fixation, oceanic primary productivity, and methane cycling are catalyzed through the activity of microorganisms. However, the composition of microbial communities and their role in structuring ecosystems and the Earth's climate are poorly understood. Our research is focused on understanding microbial processes in terrestrial, marine, and extreme ecosystems. It spans the study of lignocellulose degradation by termite gut microbiota, anaerobic cycling of carbon, nitrogen, and sulfur in microbial mats and sediments, and methane cycling in the ocean.
Biogeochemical research ranges in scale from microbial to global systems. Our current research interests include the marine carbon cycle and its geochemical record in organic matter and carbonate minerals; microbial recycling of nutrients and carbon; development and use of geochemical proxies for understanding the ancient environment, including its climate; and development of new methods for study of the global carbon cycle.
Investigating Landscape Change
Around the world, the land surface evolves in response to tectonic, climatic, biological and anthropogenic influences. We use field and laboratory measurements to build and test quantitative models for the processes that cause landscape change. Active research questions include: Will river deltas and coastal landscapes drown due to sea level rise? How will arctic rivers respond to permafrost melting? Why do debris flows occur after wildfire? How do river floodplains naturally buffer climate through organic carbon sequestration?
Tools and Facilities
Earth Surface Dynamics Laboratory
The Caltech Earth Surface Dynamics Laboratory is a 4000 sq. ft. high-bay space designed to facilitate physical experiments and models in order to study the processes that shape landscapes through erosion and deposition. The lab includes a state-of-the-art tilting flume to investigate fluvial bedrock erosion, sediment transport in rivers, and initiation of debris flows. The lab also includes a river basin for research into delta formation, river meandering, and alluvial fan evolution and stratigraphy.
Environmental Microbiology Laboratories
In the environmental microbiology laboratories, the diversity and metabolic activities of microorganisms from terrestrial and marine ecosystems are characterized through cultivation, microscopic imaging, metagenomics, and molecular and isotopic analysis. Researchers use an array of instruments, including anaerobic chambers, platforms for performing microfluidics-based analyses of the nucleic acid contents of environmental single cells, capillary sequencers, quantitative PCR, epifluorescence microscopes, and CAMECA secondary ion mass spectrometers available through the Center for Microanalysis.
The Biogeochemical Laboratories provide facilities and instrumentation for measuring the abundance, identity, and stable-isotope composition (including 2H, 13C, 15N, 18O, and 34S) of organic and inorganic constituents in a variety of environmental sample types, including organisms, water, sediments, and rocks.