Sea salt is composed of hundreds of chemical species that show a great diversity in their behavior and distribution. While seemingly benign, the question of "Why is the ocean salty?" is a dynamic and evolving area of research. For instance, we measure the isotopic composition of iron in the ocean to probe how this "micronutrient" limits the productivity of marine plants. Our investigation of the oceanic sulfur cycle tries to constrain this element's important role in preserving organic matter in marine sediments, ultimately leading to the formation of oil and the accumulation of oxygen in the atmosphere.
The ocean circulation influences the Earth's climate through its vast capacity to store heat, its exchange of trace gases with the atmosphere and its impact on marine ecosystems. The distribution of ocean properties depends on both broad, basin-wide currents that transport water masses between the equator and poles as well as smaller features, such as eddies and fronts, that control air-sea interactions. Our work includes studies about controls on the ocean's global overturning circulation, ocean-ice interactions in the ocean's polar regions, the impact of upper ocean turbulence on biogeochemical cycling, and unique methods for observing ocean, such as acoustic tomography. Our research encompasses theoretical, numerical, and observational approaches, the latter including autonomous platforms and satellite data.
Tools and Facilities
Resnick Water and Environment Laboratory (WEL)
The Resnick Water and Environment Laboratory (WEL), formally Environmental Analysis Center, is the state-of-the-art facility that supports a diverse research portfolio at Caltech. WEL is located in the Linde Center laboratory for Global Environmental Science Building. Dr. Nathan Dalleska is WEL's Director. To learn more about the laboratory, instrumentation, and user rates, please visit the Resnick Sustainability Institute WEL website.
Measurements of trace metals in the environment and precise dating of corals and cave deposits all require extremely clean conditions for processing samples. The clean room, custom designed for this purpose, is unlike any built earlier. It has air cleansed of almost all particles and has been constructed entirely from non-metallic materials. Measurements of corals and stalagmites in it reveal how climate has varied in Earth's past and how carbon cycles between the biosphere, the atmosphere, and the oceans.
Geochemistry Instrument Lab
The instrument lab houses three inductively coupled plasma mass spectrometers (ICP-MS). They are used to measure metal isotope ratios and Uranium-Thorium (U-Th) dates of samples that have been chemically processed in the clean room. They are also used to measure sulfur isotopes in the modern ocean and in ancient rocks to develop a quantitative understanding of how oxygen levels in the atmosphere have evolved over Earth's history.
Coral Culturing and Analysis
We have coupled two disparate techniques, growing corals in controlled cultures and nanoscale analysis of metals and isotopes via Secondary Ion Mass Spectrometry (nanoSIMS), to probe the way corals make their skeletons. Our goal is to understand how chemical tracers are incorporated into living coral hard parts to better understand how to read them for the record of past climate change in the oceans. In addition, as ocean acidification is a certain outcome of burning fossil fuels, we hope to understand how corals will react to their future environment, perhaps even finding the telltale signals of stress in the trace metal chemistry of their skeletons.stratigraphy.
Underwater ocean gliders are autonomous vehicles that achieve low-power propulsion through the use of wings and buoyancy changes to convert vertical motion to horizontal. This allows gliders to sample water properties, such as temperature and salinity, for periods of months while being "piloted" remotely through satellite communications. Glider networks are proving invaluable in providing high spatial and temporal resolution observations of sub-surface ocean dynamics.
Caltech High Performance Computing
The mission of the High Performance Computing Center at Caltech is to support the research efforts of scientists performing sponsored research.