UCD Stable Isotope Laboratory

My research focuses on developing and applying trace metals and stable isotopes in biogenic calcite as proxies of ocean pH and temperature. My ultimate goal is to quantify changes in ocean carbonate chemistry and explore the linkages between these changes and atmospheric carbon dioxide concentration, ocean circulation, and climate change. I'm particulary interested in how metals (especially U, Mg, and Sr) are incorporated into calcite and aragonite, and how environmental conditions in the water column and in the sediment influence the amount of these metals incorporated into marine animals.

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Tessa M. Hill

Current Research:

Recent (late Quaternary to modern) marine environmental change, utilizing the geochemistry of microfossils and corals to determine rates and magnitude of climate change, the response and adaptation of species to environmental change, the role of methane hydrate in climate change and marine geological processes, and the relationships between climate in marine and terrestrial environments. Stable Isotopes δ¹⁸O, δ¹³C, δ¹⁵N, trace elements (Mg/Ca, Sr/Ca), radiocarbon, and foraminiferal species assemblages are used as proxies for temperature and geochemical changes. Interest span geological timescales (orbital, millennial, decadel), and focus on the oceanic response to climate change and associated influences on species abundances, carbon cycling, oxygenation, ocean circulation and the methane hydrate reservoir.

For more information on my ongoing research, please visit:

http://www.bml.ucdavis.edu/facresearch/hill.html

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Matthew Schmidt

Current Research:

Using Mg/Ca ratios and δ¹⁸O in the planktic foraminifera G. ruber to reconstruct temperature and salinity at three key locations in the north Atlantic: the Colombian Basin (western Caribbean); the Blake-Bahama Outer Ridge (western subtropical Atlantic); and in the central North Atlantic gyre. Primary research objectives are:

1 - on millennial time scales, to reconstruct a continuous high resolution record of salinity and temperature in the north Atlantic gyre during MIS 3 in order to link density changes in surface waters to rapid climatic change.

2 - on orbital time scales, to explore the link between salinity variation in the north Altantic and North Atlantic Deep Water formation over the last 475kyr.

Funding for this research was provided by a two-year USSSP Schlanger Ocean Drilling Fellowship and by the National Science Foundation.

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Kathryn Rose

Current Research:

Master’s Thesis: Carbon Isotope Minimum Event

The last glacial episode represents the most dramatic temperature change in recent history and can be used as a framework for understanding oscillations in the climate system and associated perturbations in the carbon cycle. Reorganizations in the ocean-atmosphere system during these rapid climate oscillations are associated with perturbations in the carbon isotope record. A characteristic feature of the deglacial record is an abrupt decrease in δ¹³C, recorded in fossil foraminifera. These low ¹³C/¹²C ratios have been documented by studies throughout the Southern Ocean (e.g. Spero & Lea, 2002; Pahnke et al., unpublished data) as the carbon isotope minimum event (CIME). The reoccurrence of the CIME on the last few glacial terminations suggests a strong linkage to processes driving the abrupt transition from glacial to interglacial climate modes. My research on the CIME will help constrain and identify the mechanisms that contribute to carbon cycling, ocean circulation and the subsequent effects on the climate system.