Andrew Jacobson

Andrew Jacobson

Professor
Director, Environmental Sciences Program
Email: adj at
earth.northwestern.edu
847-491-3132
Location: Tech F396/F398

Ph.D. Geological Sciences, University of Michigan, Ann Arbor
M.S. Earth Sciences, Dartmouth College
B.A. Earth Sciences and Chemistry, University of California, Santa Cruz

Research Website


Research

My students and I specialize in low-temperature aqueous and radiogenic isotope geochemistry. We combine fieldwork, laboratory experiments, and numerical modeling to quantify chemical, physical, and biological phenomena that cycle elements and their isotopes at the Earth’s surface. Many activities use isotopes to probe the compositional evolution of the Earth, at timescales spanning the geological to modern-day. Other projects aim to improve isotopic measurements, as well as elucidate the fundamental behavior of isotopes, including their distribution, transport, and possible fractionation within and between Earth’s biogeochemical reservoirs. A prime goal is to isotopically track the flow, transformation, and distribution of carbon. We study mineral weathering and precipitation reactions that cycle carbon and other elements, link inorganic and organic aspects of the Earth system, and control the geochemistry of soils, rivers, aquifers, seawater, and the atmosphere. Current investigations include field projects in Iceland, Greenland, and the Canadian Arctic Archipelago, as well as “deep time” studies involving the isotopic analysis of sedimentary rocks and fossils spanning major carbon cycle perturbations in Earth history.

Teaching

EARTH 201: Earth Systems Revealed (Introductory Geology)
EARTH 310: Aqueous Geochemistry
EARTH 313: Radiogenic Isotope Geochemistry

Selected Publications

Mills J. V., Gomes M. L., Kristall B., Sageman B. B., Jacobson A. D., and Hurtgen M. T. (In press) Massive volcanism, evaporite deposition, and the chemical evolution of the Early Cretaceous ocean. Geology.

Andrews M. G., Jacobson A. D., Lehn G. O., Horton T. W., and Craw D. (2016) Radiogenic and stable Sr isotope ratios (87Sr/86Sr, δ88/86Sr) as tracers of chemical weathering and biogeochemical cycling in the Milford Sound region of Fiordland, New Zealand. Geochimica et Cosmochimica Acta, 173, 284-303.

Jacobson A. D., Andrews M. G., Lehn G. O., and Holmden C. (2015) Silicate versus carbonate weathering in Iceland: New insights from Ca isotopes. Earth and Planetary Science Letters 416, 132-142.

Du Vivier A. D. C., Jacobson A. D., Lehn G. O., Selby D., Hurtgen M. T., and Sageman B. B. (2015) Ca isotope stratigraphy across the Cenomanian-Turonian OAE 2: links between volcanism, seawater geochemistry, and the carbonate fractionation factor. Earth and Planetary Science Letters 416, 121-131.

Lehn G. O., Jacobson A. D., Holmden C. (2013) Precise analysis of Ca isotope ratios (δ44/40Ca) using an optimized 43Ca-42Ca double-spike MC-TIMS method, International Journal of Mass Spectrometry 351, 69-75.

Moore J., Jacobson A. D., Holmden C., Craw D. (2013) Tracking the relationship between mountain uplift, silicate weathering, and long-term CO2 consumption with Ca isotopes: Southern Alps, New Zealand, Chemical Geology 341, 110-127.

Research Interests

  • Aqueous geochemistry
  • Stable and radiogenic isotope geochemistry
  • Climate change
August 23, 2017