Sigman Home

Department of Geosciences 
M52 Guyot Hall 
Princeton University 
Princeton, NJ 08544

Phone: (609) 258-2194
E-Mail:

Sigman studies the cycles of biologically important elements and their interaction with changing environmental conditions through the course of Earth history. His current research activities include the development of stable isotope methods by which to track the marine nitrogen cycle, today and in the past, and the construction of simple geochemical models for paleoceanographic and Earth history studies. Much of his work to date has focused on the oscillation between ice ages and interglacial periods which has dominated Earth's climate for the last two million years. These cyclic climatic changes provide an important test case for the interaction between inorganic and biological processes in setting environmental conditions on Earth. 

Ongoing studies of the nitrogen cycle in the modern ocean use the isotopic composition of dissolved nitrogen species to study (1) nitrogen cycling in the Southern Ocean and its relationship to physical circulation, (2) nitrogen transformations in sediment porewaters, (3) the nitrogen budgets of restricted marine basins and the global ocean. His studies of the history of the nitrogen cycle make use of the organic matter preserved within microfossils as a recorder of nutrient dynamics in the surface ocean. These modern and paleoceanographic studies provide complementary information on the causes and effects of changes in the marine nitrogen cycle. 

There have been two components to Sigman's geochemical modeling efforts. The first component involves the coupled effects of upper ocean biology and the chemistry of deep sea sediments on the carbon dioxide content of the atmosphere. The second component centers on the use of geochemical data to constrain changes in deep ocean circulation over the last ice age/interglacial transition. Recently, he has begun work on the incorporation of nitrogen isotopic constraints into models of the modern and ancient ocean. 

From the Smilodon, Fall 2001: Ocean Nutrient Cycling: Today and in the Past

Current research in the Sigman lab