Heather M. Stoll Dept de Geologia Universidad de Oviedo Arias de Velasco s/n 33005 Oviedo Asturias Spain hstoll@geol.uniovi.es +34 985 10 2867 (phone) +34 985 10 3103 (fax) Research Projects Experience Publications
Research Projects
Marine productivity and the carbon cycle Algal evolution		Past hydrological changes recorded in stalagmites
Marine productivity and the carbon cycle I have worked on developing new indicators for productivity variations from the chemistry of calcite coccoliths produced by marine coccolithophorid algae. I have used laboratory cultures and sediment trap time series for verification, and applied these indicators to study past productivity variations in the Quaternary Arabian Sea and Bay of Bengal and over the Paleocene-Eocene Thermal Maximum. As part of this work, we developed a new method for picking individual coccoliths with a micromanipulator, and mounting them for trace element analysis via ion probe (SIMS) in collaboration with Nobu Shimizu at Woods Hole Oceanographic Institute. Funding sources U.S. NSF and Petroleum Research Fund.
Algal evolution If current trends continue, over the next few centuries atmospheric CO2 from will likely to reach levels last seen tens of millions of years ago. Evidence suggests that modern calcifying algae and diatoms employ a range of carbon acquisition strategies (such as active carbon concentrating mechanisms) according to their cell geometry and the pH and carbon speciation of the seawater in which they live. However, we have observed that calcifying algae from 60 million years ago apparently had a single or less diverse array of carbon acquisition strategies. The project will identify and calibrate novel geochemical fossil indicators for adaptation and evolution in carbon acquisition strategies in eukaryotic algae, and apply these indicators to establish the magnitude, rate, and timing of changes in carbon acquisition strategies by algae in response to past changes in the carbon cycle and atmospheric CO2 over the past 60 million years. Funding source is ERC- EC VII Plan Marco. Positions are available in this project.
Past Hydrological Changes Recorded in Stalagmites We are working to reconstruct past changes in hydrological balance (P-E) and precipitation dynamics (moisture source) in NW Spain, from orbital timescales to multidecadal variations over the last few millennia. This region is sensitive to NAO influence and potential orbital excitation of climate modes. We are also working to ascertain if the frequency of extreme precipitation events leading to floods can be reconstructed from stalagmites. Dripwater monitoring, with a device we designed, has been conducted in various caves since 2003 and synoptic scale rainwater isotope monitoring since 2006. This project is in collaboration with geomorphology group at Oviedo (Montse Jimenez, Maria Jose Dominguez), dating expertise at U. Minnesota (R. Larry Edwards, Hai Chang), and others (Ana Moreno, Steve Burns, Ricardo Trigo, Ana Mendez). Principal funding is from Spanish Ministry of Science and Asturias government regional science ministry.
Experience and Awards PhD, Princeton University, 1998 Gretchen Bletchschmidt Award, GSA, 1996 NATO-NSF Postdoctoral Fellowship, 1998-2000 EGU Outstanding Young Scientist Award, 2006 DuPont Young Professor Award, 2008 ERC Starting Investigator Award, 2009 Teaching Experience: Williams College: (tenure awarded): The Carbon Cycle, Climate Changes, Environmental Geology, Introduction to Environmental Science Univ. of Oviedo: Masters courses in Climate Change, Marine Biogeochemical Cycles and Paleoceanography
Publications Published In review Published Rudzka, D., McDermott, F., Baldini, L.M., Fleitmann, D., Moreno, A. and Stoll,H. A coupled 13C-radiocarbon investigation of cave and soil processes recorded by three European speleothems during the Late Glacial and early Holocene. Quaternary Science Reviews, 2011. Stoll, H.M. Ion Partitioning and trace element proxies in foraminifera and coccoliths, in Prieto, M., and Stoll, H. Eds. Ion Partitioning in Ambient-Temperature Aqueous Systems. European Mineralogical Union, 2010. Moreno, A., Stoll, H., Jimenez-Sanchez, M., Cacho, I., Valero-Garces, B., Ito, E., and Edwards, R.L. A speleothem record of glacial rapid climatic changes from Northern Iberian Peninsula, Global and Planetary Change, 2010. Gibbs, S., Stoll, H.M., Bown, P., and Bralower, T. Surface water saturation state and carbonate production across the Paleocene-Eocene Thermal Maximum. Earth and Planetary Science Letters, 2010. Auliaherliaty, L.** Stoll, H.M., Ziveri, P. et al. Coccolith Sr/Ca ratios in Eastern Mediterranean: production vs. export processes. Marine Micropaleontology 73, 196-206, 2009. Stoll, H.M. and Shimizu, N. Micro-picking of nannofossils in preparation for analysis by secondary ion mass spectrometry. Nature Protocols, 2009. Moreno, A., Valero-Garces, B., Jimenez-Sanchez, M., Dominguez, M.J., Mata, P., Navas, A., Gonzalez-Samperiz, P., Stoll, H., Farias, P., Morellon, M., Corella, J., Rico, M. The last deglaciation in the Picos de Europa National Park (Cantabrian Mountains, Northern Spain). Journal of Quaternary Science, 2009. Langer, G., Nehrke, G., Thoms, S., Stoll, H. Ba partitioning in coccoliths of Emiliania huxleyi. Geochimica et Cosmochimica Acta, 2009. Stoll, H.M., Shimizu, N., Ziveri, P., and Archer, D. Coccolithophore Productivity Response to Greenhouse Event of the Paleocene-Eocene Thermal Maximum, Earth and Planetary Science Letters,258, p. 192-206, 2007. Stoll, H.M., Vance, D. and Arevalos, A.’05 Nd isotope records from Bay of Bengal constrain effect of Northern Hemisphere cooling on ITCZ movement. Earth and Planetary Science Letters 255, 213-228, 2007. Stoll, H.M., Ziveri, P., Shimizu, N., Conte, M., and Theroux, S’05. Relationship between coccolith Sr/Ca ratios and coccolithophore production and export in the Arabian Sea and Sargasso Sea, Deep Sea Research II 54, p. 581-600. (Special Issue on Role of Marine Organic Carbon and Calcite Fluxes in Driving Global Climate Change, Past and Future), 2007. Ziveri, P., DeBernardi, B., Baumann, K., Stoll, H.M., and Mortyn, P.G. Sinking of coccolith carbonate and potential contribution to organic carbon ballasting in the deep ocean. Deep Sea Research II 54, p. 659-675. (Special Issue on Role of Marine Organic Carbon and Calcite Fluxes in Driving Global Climate Change, Past and Future), 2007. Stoll, H.M., Arevalos, A.’05, Burke,A.’06, Ziveri, P., Mortyn, P.G., Shimizu, N. and Unger,D. Seasonal Cycle of Coccolithophorid and Biogenic Carbonate Productivity in Bay of Bengal Sediment Traps. Deep Sea Research II 54, (Special Issue on Role of Marine Organic Carbon and Calcite Fluxes in Driving Global Climate Change, Past and Future), 2007. Stoll, H.M., Shimizu, N., Arevalos, A.’05, MatellN.’06, Banasiak,A.’08, and Zeren, S. ‘05Insights on Coccolith Chemistry from a New Ion Probe Method for Analysis of Individually Picked Coccoliths. Geochemistry Geophysics Geosystems, 8, Q06020, doi:10.1029/2006GC001546, 2007. (como la biblioteca no recibe esta revista he incluido mi “proof” y la portada disponible en pagina web de la revista) Stoll, H.M. Climate Change: The Arctic tells its story (News and Views). Nature, 441, 579-581. Stoll, H.M. Limited range of interspecific vital effects in coccolith stable isotopic records during the Paleocene-Eocene Thermal Maximum. Paleoceanography, doi 10/1029PA2004001046, 2005 Stoll, H.M. Response to comment on “Coccolith Sr/Ca records of productivity during the Paleocene-Eocene Thermal Maximum from the Weddell Sea”. Paleoceanography, v.19 doi 10.1029/2003PA000971, 2004. Stoll, H.M. and Bains, S.Coccolith Sr/Ca records of productivity during the Paleocene-Eocene Thermal Maximum from the Weddell Sea Paleoceanography, v. 18 doi 10.1029/2002PA000875, 2003. Ziveri, P*., Stoll, H.M*., Probert I. , Klaas, C., Geisen, M., Young J., and Ganssen, G. Stable Isotope Vital Effects in Coccolith Calcite. Earth and Planetary Science Letters 210, p. 137-149, 2003. (authors marked with asterisk contributed equally to this work as noted in the article) Stoll, H.M., Ziveri, P., Geisen, M., Probert, I., and Young, J.R. Potential and limitations of Sr/Ca ratios in coccolith carbonate: new perspectives from cultures and monospecific samples from sediments. Phil. Trans. Roy. Soc. of Lond. A 360, 719-747, 2002. Stoll, H.M., Rosenthal, Y., and Falkowski, P. "Climate proxies from Sr/Ca of coccolith calcite: calibrations from continuous culture of Emiliania huxleyi." Geochimica et Cosmochimica Acta, 66, 927-936, 2002. Stoll, H.M. and Ziveri, P. Separation of mono-specific and restricted coccolith assemblages from sediments using differential settling velocity Marine Micropaleontology, 46, 209-221, 2002. Stoll, H.M, Ruiz-Encinar, J., Garcia-Alonso, J.I., Rosenthal, Y., Klaas, C., and Probert, I. A first look at paleotemperature prospects from Mg in coccolith carbonate: cleaning techniques and culture measurements. Geochemistry, Geophysics, Geosystems, 2001. Stoll, H.M, Klaas, C., Probert, I. P.,Ruiz-Encinar, J., Garcia-Alonso, J.I.Calcification rate and temperature effects on Sr partitioning in coccoliths of multiple species of coccolithophorids in culture. Global and Planetary Change 34, 153-171, 2002. Stoll, H.M. and Schrag, D.P. Sr/Ca variations in Cretaceous carbonates: relation to productivity and sea level changes. Palaeogeography, Palaeoclimatology, Palaeoecology 168, 311-336, 2001. Stoll, H. M., and D.P. Schrag, Coccolith Sr/Ca as a new indicator of coccolithophorid calcification and growth rate. Geochemistry Geophysics Geosystems, 1, 1-24, 2000. Stoll, H. M. and D. P. Schrag. High resolution stable isotope records from the Upper Cretaceous of Italy and Spain: Glacial episodes in a greenhouse planet? GSA Bulletin, 112, 308-319, 2000. Stoll, H. M., D. P. Schrag, and S. C. Clemens, Are seawater Sr/Ca variations preserved in Quaternary foraminifera? Geochimica et Cosmochimica Acta, 63, 3535-3547, 1999. Stoll, H. M. and D. P. Schrag, Effect of Quaternary sea level cycles on the Sr budget of the ocean. Geochimica et Cosmochimica Acta, 62, 1107-1118, 1998. Karabinos, P., S.D. Samson, J.C. Hepburn, and H. M. Stoll. Taconian orogeny in the New England Appalachians: Collision between Laurentia and the Shelburne Falls Arc. Geology, 26, 215-218, 1998. Stoll, H. M. and D. P. Schrag, Evidence for Glacial Control of Rapid Sea Level Changes in the Early Cretaceous. Science, 272, 1771-1774, 1996. In review Graduate students in italics Stoll, H.M., Langer, G., Shimizu, N, and Kanamaru, K. B/Ca ratios in coccoliths and relationship to calcification vesicle pH and dissolved inorganic carbon. Geochimica et Cosmochimica Acta, in review Dedert, M.**, Stoll, H.M., Ziveri, P. Productivity response of calcareous nannofossil response to early Eocene Thermal event (EMT2) Elmo at Site 1265A, Walvis Ridge. Journal of Past Climates, in review. Dedert, M., Stoll, H.M., Ziveri, P. Productivity response of calcareous nannofossil response to early Eocene Thermal event (EMT2) Elmo at Site 1265A, Walvis Ridge. Earth and Planetary Science Letters, in review.