Environmental Science and Engineering

Research and teaching in the ESE program span the large scales of global climate variations, the local scales of urban air pollution, and the microscales of microbial ecosystems. Reflecting the interdisciplinary nature of the ESE program, it unites scientists and engineers from Caltech’s Division of Geological and Planetary Sciences, Division of Engineering and Applied Science, and Division of Chemistry and Chemical Engineering. Jointly they address, for example, how climate has varied in the past and how it may change in the future, how biogeochemical cycles and chemical reactions control the composition of the atmosphere and local air quality as well as the Earth’s global energy balance, and how more efficient and effective ways of producing biofuels or remediating toxic waste can be found. The methods employed in research projects include laboratory studies of fundamental chemical and biological processes; field studies of microbial ecology and of atmospheric chemistry; and computational and theoretical studies of chemical and physical processes on molecular to global scales.

Students enter the ESE program with diverse backgrounds, from the basic sciences of physics, chemistry, and biology to applied science and engineering fields. The curriculum emphasizes interdisciplinary knowledge and is broad, yet it is flexible so that different backgrounds and focus areas can be accommodated.

• Atmospheric Chemistry and Air Pollution. Atmospheric chemistry affects the composition of the atmosphere, properties of clouds, and local air quality. Research areas include cloud chemistry, aerosol chemistry and physics, trace gas photochemistry, and emission sources and transport and reaction pathways of organic species. The methods employed include laboratory studies of aerosol formation and of chemical reactions in the atmosphere; field campaigns with aircraft operated by ESE faculty; satellite missions carried out in collaboration with the Jet Propulsion Laboratory; and theoretical and modeling studies of tropospheric chemistry and the carbon cycle.
• Environmental Chemistry and Technology. Environmental chemistry and technology research in ESE addresses fundamental questions in heterogeneous atmospheric chemistry (e.g., chemistry of clouds, fogs, and haze aerosols), in aquatic chemistry, in oxidation and reduction chemistry and technology, in semiconductor photocatalysis, and in hydrogen production from sunlight via electrochemical water splitting.
• Dynamics of Climate. Climate dynamics research in ESE addresses fundamental questions about how Earth’s climatic features are maintained, how they have varied in the past, and how they may change in the future. Research includes the large-scale dynamics of the atmosphere and oceans, the hydrologic cycle and how it responds to climate changes, monsoon dynamics, and the dynamics of the Southern Ocean, and climates of other planets. Methods employed include theoretical and modeling studies, analyses of observational data, and field campaigns to collect oceanographic data.
• Biogeochemistry and Climates of the Past. Biogeochemical research in ESE finds application at scales ranging from microbial ecosystems to the global carbon cycle. Current research interests include the marine carbon cycle and its geochemical record in organic matter and carbonate minerals; microbial recycling of nutrients and carbon; and development and use of geochemical proxies for understanding the ancient environment, including its climate.
• Environmental Microbiology. Microorganisms are the primary drivers of global biogeochemical cycles and represent the most abundant and diverse forms of life on Earth. They catalyze critical biological transformation processes such as nitrogen fixation, oceanic primary productivity, and methane cycling. Microbial ecosystem research within ESE is focused on understanding microbial processes in terrestrial, marine, and extreme ecosystems. Research areas span a range of topics and field sites, including 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.
  

ESE laboratories and facilities are housed in the Ronald and Maxine Linde Laboratory for Global Environmental Science and in other nearby buildings of Caltech’s Division of Geological and Planetary Sciences. The laboratories are equipped with a wide variety of state-of-the-art instruments.

• The Environmental Analysis Center (EAC) houses analytical instrumentation, for research that ranges from analyzing pollutants in groundwater to dating fossils. Its equipment includes instruments for electrochemistry, plasma emission mass spectrophotometry, gas chromatography, high-performance liquid chromatography, fluorescence spectroscopy, infrared spectrometry, gas chromatography–mass spectrometry, total organic carbon analysis, and electrophoresis and electrical particle size analysis. Scientists from across the Institute use the EAC for cutting-edge analytical studies.
• The Atmospheric Chemistry and Aerosol Laboratory is designed for studies of the photochemical reactions of gaseous and particulate pollutants. In two reaction chambers (28 m³ each)—the first of their kind when they were built—the chemical reactions that produce urban smog and atmospheric particles are investigated under precisely controllable conditions. They have revealed how the particles that make up smog form in the atmosphere. Research results obtained with them have been instrumental in designing effective air quality policies. They continue to be invaluable in studies of air pollution.
• The High-Precision Spectroscopy Laboratory is housed in a quiet room—a room with specially designed acoustic and electromagnetic insulation. Acoustic foam blocks sound waves and copper cladding around the entire room blocks electromagnetic waves. The noise-free environment allows us to achieve exquisite precision in laser measurements of radiative properties of greenhouse gases, aerosols, and atmospheric trace constituents: the properties of single molecules can be measured. The measurements are the basis for climate models and for planning satellite missions to measure the composition of the atmosphere from space.
• In the Laboratory for Atmospheric Chemical Physics, the interactions of light with molecules in the atmosphere are investigated to elucidate how pollution forms and to measure the atmospheric concentration of aerosols and greenhouse gases. Techniques are developed for the global monitoring of the atmosphere from mobile ground-based laboratories and from space-based instruments.
• In the Environmental Chemistry and Technology Laboratory, collimated sunlight from the Linde + Robinson solar telescope is focused into photolysis reactors, where artificial photosynthesis processes are developed to convert water and carbon dioxide into energetic fuels. Additionally, the chemical nature of the air-water interface is studied, and new technologies are developed for storing electric energy in novel lithium-air batteries and for treating water, for example, by photovoltaically powered electrolysis or ultrasonically induced cavitation.
• The Geochemistry Clean Room is designed for trace metal analysis in an entirely metal-free environment. It has air cleansed of almost all particles, to be able to measure with high precision tiny traces of metals and radioactive isotopes found in ocean water and embedded in corals and in stalagmites. These measurements reveal information about how climate has varied in Earth’s past and how carbon cycles between the biosphere, the atmosphere, and the oceans. The Clean Room is supported by a plasma mass spectrometry instrument room that contains two multi-collector instruments and a quadrapole instrument. The facility also contains a wet chemistry laboratory for the processing and analysis of environmental samples.
• The Biogeochemistry Laboratories provide capabilities for analyzing the structure, abundance, and isotopic composition of organic materials in environmental samples, ranging from organisms to sediments to rocks. Instrumentation includes gas chromatograph–mass spectrometers, isotope-ratio mass spectrometers with capabilities for bulk and compound-specific analysis, a spectroscopic water isotope analyzer, and a combustion elemental analyzer.
• 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. Instrumentation includes 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 (7f Geo and nanoSIMS 50L) available through the Center for Microanalysis.
• Fram High Performance Computing (HPC) Cluster. Fram is a (HPC) Cluster composed of 314 HP SL390 computer nodes with 12 cores available per node. The cluster is connected with a low latency, high bandwidth network called InfiniBand. In addition to the traditional computer nodes, it also has 60 GPU based nodes with a total of 180 Nvidia M2090 GPUs. This filesystem can perform at around 9.5 GB/s. Fram is the latest of many clusters used for analysis and simulation of climate dynamics.
  

Additionally, Caltech collaborates with the Naval Postgraduate School’s Center for Interdisciplinary Remotely Piloted Aircraft Studies (Monterey, California). This center operates research aircraft for atmosphere science studies, including a Twin Otter aircraft that carries state-of-the-art instruments to measure atmospheric aerosol and cloud properties in situ. Faculty, students, and staff in the ESE program also have access to the supercomputer facility of the Division of Geological and Planetary Sciences, where they carry out simulations of dynamical processes in the atmosphere and oceans and of chemical reactions and transport processes affecting atmospheric chemistry.