Meet the Researchers

Matt Alkire

team_AlkireMatthew B. Alkire, Ph.D.

Polar Science Center
Applied Physics Laboratory
University of Washington
1013 NE 40th Street
Seattle, WA 98105
tel: (206) 897-1623

About Matt

My research focuses mainly on the use of inorganic chemical tracers (stable oxygen isotopes, total alkalinity, barium, dissolved oxygen and nutrients) to distinguish and quantify the contribution of various sources of freshwater to the Arctic Ocean. Freshwater in the Arctic comes from a number of sources, including river runoff from Alaska, Canada, and Russia, sea ice melt, precipitation (rain and snow), glacial melt, and Pacific water. These freshwaters play important roles in stratification, halocline water formation, biological production, CO2 uptake and sequestration, and ocean acidification. We can understand more about the Arctic’s response to changing climate by monitoring changes to the input, distribution, and export of each individual freshwater source.

At present, I have three active research projects that:

(1) Investigates the potential for smaller Arctic rivers to have significantly different chemical signatures than the much larger rivers of North America

(2) Monitors the interannual variability in the physical and chemical hydrographic structure of the central Arctic Ocean

(3) Studies the interaction, mixing, and transformation of Atlantic and shelf waters on the Siberian continental shelf and slope.

Although the majority of my work focuses on the Arctic Ocean, I also have research interests in the use of autonomous platforms (e.g., floats and gliders) to study the production and export of carbon in the world ocean.

Andy Jacobson

team_jacobsonAndrew D. Jacobson, Ph.D.

Associate Professor and Director of the Environmental Sciences Program
Department of Earth and Planetary Sciences
Northwestern University
2145 N. Sheridan Road
Evanston, IL  60208-3130
Phone: 847-491-3132
FAX: 847-491-8060

About Andy

My students and I specialize in aqueous and radiogenic isotope geochemistry. We combine fieldwork, laboratory experiments, and 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 human. Others aim to elucidate the fundamental behavior of isotopes themselves, including their distribution, transport, and possible fractionation within and between Earth’s biogeochemical reservoirs. Of prime interest is isotopically tracking the flow, transformation, and distribution of carbon. Several projects focus on 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. Related efforts seek to understand the causes and consequences of climate change in deep time and the modern day.

Greg Lehn

team_lehnGregory O. Lehn, Ph.D. Candidate

Department of Earth and Planetary Sciences
Northwestern University
2145 N. Sheridan Road
Evanston, IL 60208-3130
Phone: 847-467-2467
FAX: 847-491-8060

About Greg

My research interests include the use of geochemical mineral weathering products, elemental and isotopic (Ca, Sr, and C), to study seasonal and long-term changes in the terrestrial Arctic systems. These tracers allow unique insight into the connections between the geosphere, hydrosphere, and biosphere, to understand how northern Alaskan soils and rivers will respond to amplified Arctic warming and the implications for the global carbon cycle. I am also interested in the further development of high-precision isotope methods to further increase the resolution and functionality of Ca and Sr as geochemical tracers.


Robie Macdonald

Profile Image

Robie Macdonald, Ph.D.

Phone: (250) 363-6409
Fax: (250) 363-6409
Region: Pacific
Office: Institute of Ocean Sciences
Field(s) of Research:

  • Aquatic Ecosystems Science
  • Ocean Climate
  • Physical Oceanography
Research Description:

Dr. Macdonald directs interdisciplinary programs to study the environmental pathways of contaminants including their delivery, transport, and elimination from aquatic systems. A variety of settings are studied including Arctic shelves and basins, British Columbia fjords, the Strait of Georgia, and lakes in the Fraser River basin. He determines the behaviour of contaminants in the context of natural systems bringing to bear such tools as water-mass analysis, transient and steady state tracers, stable isotope analyses (oxygen, carbon and lead), the determination of particle fluxes and sedimentation rates, multivariate statistics and modeling. Most of the major contaminant groups have been studied including PAH, metals, radionuclides, organochlorines, and other synthetic organic compounds like the nonylphenol ethoxylates. Dr. Macdonald focuses on site-specific contaminant sources including chlor-alkali plants, pulp mills, mine-tailing disposal and municipal outfalls, as well as broader contaminant issues such as long-range atmospheric transport of semi-volatile contaminants to the Arctic Ocean and Georgia Basin, and the potential impacts of oil exploration on Canada’s western Arctic shelves. Contaminants are studied according to how they enter and leave natural water bodies and how they impinge on natural biogeochemical cycles. Multivariate statistical techniques as well as dated sediment cores are used to distinguish between anthropogenic contaminants and their natural counterparts. Often, more than one anthropogenic source contributes to contaminant loadings, in which case the same techniques are used to work out the relative strength of each source. Insight and data developed through these studies is incorporated into national and international environmental assessments. Dr. Macdonald is currently based out of the Institute for Ocean Sciences (IOS) and also is a professor at the University of Manitoba and University of Victoria.