Matthew J. Evans
Assistant Professor of Chemistry and Geology
Ph.D., M.S., Geochemistry, Cornell University
B.A., Geology, Middlebury College
I am a geochemist interested in understanding the interaction between water and rocks at the surface and near-surface of the Earth. Using major and trace elements, as well as stable and radiogenic isotopes, I examine weathering and the release and fate of solutes in large and small river basins. In particular, I have investigated the impact that the relatively small-scale hydrothermal system in central Nepal has on weathering budgets and carbon dioxide uptake. I am also interested in the overall physical and chemical impact that humans have on the natural hydrologic system.
These interests have led to two funded research projects:
With colleagues at Cornell University we have been funded by NSF to examine the geothermal system along the Himalayan front. This research group has shown that geothermal springs in major river valleys near the Main Central Thrust zone of the Himalayan front are significant sources of carbon dioxide (see publications list). To date we have shown that this source of CO2 exceeds the consumption of CO2 by chemical weathering in the large Narayani basin of central Nepal. Investigators have proposed that the source of this large CO2 flux is metamorphic decarbonation and decarboxylation reactions which take place in the subducted Lesser Himalyan sediments beneath the Himalayan front. In at least this region of the Himalaya, the net flux of CO2 from the carbonate-silicate cycle is strongly positive, in contrast to the widely held view that the Himalaya are an important CO2 sink. We are investigating hot springs and rivers across the Himalayan range, including Bhutan and NW India, to address the issue of along-strike heterogeneity of the CO2 flux in Himalayan geothermal systems and greatly improve estimates of the overall carbon balance. Wheaton Quarterly article.
Working with researchers at the Woods Hole Oceanographic Institute and Clark University, I am involved in a NASA funded project examining the interaction between the West Antarctic Ice Sheet (WAIS) and the adjacent marine cryosphere. This dynamic coupled system is undergoing dramatic change, with significant increases in ice-mass loss, and recent shifts in Southern Ocean sea ice cover impacting ocean-atmosphere energy fluxes, ocean circulation and marine biological productivity. Our ability to predict future changes in ice sheet mass balance and sea level rise; changes in freshwater fluxes between the Antarctic Ice Sheet and the Southern Ocean; and ocean circulation and marine biogeochemistry even over the next 100 years is severely limited not only by the large natural variability of polar climate, but by a lack of understanding of how the components of the polar cryosphere (particularly ice sheets and sea ice) interact with one other, as well as how they will respond to this climate variability. We are using overlapping satellite and ground-based observations and chemical analyses to investigate sea-ice variability (concentration, and the timing of melt onset, breakup, and freeze), sea-surface variability (sea surface temperature (SST), surface water chlorophyll biomass and primary productivity) and ice-sheet variability (accumulation, surface melting, and ice sheet temperature). At Wheaton, my students and I are performing chemical analyses of MSA in ice and snow samples to produce a proxy for marine productivity. Wheaton Quarterly article.
Geochemistry, Environmental and Analytical Chemistry, Hydrology, Environmental Geology.
- A. S. Criscitiello, S. B. Das, M. J. Evans, K. E. Frey, H. Conway, I. Joughin, B. Medley, E. J. Steig (2013), Ice sheet record of recent polynya variability in the Amundsen Sea and Pine Island Bay, West Antarctica, Journal of Geophysical Research-Oceans, 188, 1-13, doi:10.1029/2012JC008077.
-L. A. Derry, M. J. Evans, R. Darling, C. France-Lanord, Hydrothermal heat flow near the Main Central Thrust, central Nepal Himalaya, Earth and Planetary Science Letters, 286, 101-109, 2009.
-M. J. Evans, L. A. Derry, C. France-Lanord, Degassing of metamorphic carbon dioxide from the Nepal Himalaya, Geochemistry, Geophysics, Geosystems, 9 (4), 1-18, 2008. Q04021, doi:10.1029/2007GC001796
*One of two featured articles in Science Perspectives, 27 June 2008: vol. 320 #5884 1727-1728
-K. Attoh, M. J. Evans, and M. E. Bickford. Geochemistry of an ultramafic-rodingite rock association in the Paleoproterozoic Dixcove greenstone belt, southwestern Ghana, Journal of African Earth Sciences, 45 (3), 333-346, 2006.
-M. J. Evans, L. A. Derry, C. France-Lanord, Geothermal fluxes of alkalinity in the Narayani river system of central Nepal, Geochemistry, Geophysics, Geosystems, 5 (8), 1-21, 2004. Q08011, doi:10.1029/2004GC000719
-C. France-Lanord, M. Evans, J.E. Hurtrez, J. Riotte, Annual dissolved fluxes from Central Nepal rivers: budget of chemical erosion in the Himalayas, Comptes Rendus Geoscience, 335 (16), 1131–1140, 2003.
-J. Kim, R. Coish., M. Evans, G. Dick, Supra-subduction zone extensional magmatism in Vermont and adjacent Quebec: Implications for early Paleozoic Appalachian tectonics, GSA Bulletin, 115 (12), 1552–1569, 2003.
-M. J. Evans, L. A. Derry, Quartz control of high germanium-silicon ratios in geothermal waters, Geology, 30 (11), 1019–1022, 2002.
-M. J. Evans, L. A. Derry, S. P. Anderson and C. France-Lanord, A hydrothermal source of radiogenic Sr to Himalayan rivers, Geology, 29 (9), 807–810, 2001.