Developing a Network of n-Alkane Hydrogen Isotope Records to Identify Drivers and Impacts of Holocene Droughts

(NSF-1660185)

This project will address patterns and drivers of past droughts and their effects on humans and the biosphere. The researchers will analyze lake-sediment cores to develop records of precipitation variability associated with past shifts in major drivers of atmospheric circulation that influenced the broader circum-Caribbean region, including the U.S. Gulf Coast. The precipitation records will be compared to evidence of past human activity and biomass burning in lake watersheds, to explore local consequences of regional shifts in atmospheric drivers. The work will form the foundation for an expanded network of precipitation reconstructions across the region that will allow examination of processes at a larger spatial scale and of additional drivers. The project will provide experience in multi-laboratory collaborative research to four faculty and ten or more graduate and undergraduate students. Results from project activities will be broadly disseminated in publications and presentations. The researchers will share scientific knowledge of past environmental change with K-12 students and teachers in Tennessee and North Carolina through outreach projects that will include hands-on activities and authentic research.

The researchers will develop precipitation records using compound-specific hydrogen isotope analyses of n-alkanes in lipids in sediment cores from five lakes along two transects that cross climate and ecosystem regions. Hydrogen isotope analysis of lipids in sediment cores is an alternative to oxygen isotope analysis of biogenic carbonates that can be applied in a wide variety of lakes, making possible the development of a network of sites using the same precipitation proxy. The hydrogen isotope records will be produced from existing cores from lakes in Costa Rica, and will serve as the western anchor in a larger network of precipitation records that the researchers plan to develop through the broader circum-Caribbean region, including the U.S. Gulf Coastal Plain. The hydrogen isotope analyses will document the geography of multi-decadal drought during the Terminal Classic Drought (~1200-850 cal yr BP), the Little Ice Age (~500-100 cal yr BP), and at other times, and reveal whether these were exceptional or outlier droughts for the Holocene as a whole. Comparison with local paleoenvironmental and archaeological evidence will show how past droughts affected vegetation, fire regimes, and prehistoric agriculture.

Personnel Related to the Project:

Principal Investigators

Dr. Sally P. Horn, Professor, Department of Geography, University of Tennessee-Knoxville

Dr. Chad S. Lane, Associate Professor, Department of Earth and Ocean Sciences, University of North Carolina Wilmington

Dr. Douglas W. Gamble, Professor and Chair, Department of Earth and Ocean Sciences, University of North Carolina Wilmington

Faculty Associate:

Dr. Erik Johanson, Assistant Professor, Department of Geocsciences, Florida Atlantic University

Graduate Research Assistants:

Matthew Kerr, Ph.D. Student, Department of Geography, University of Tennessee-Knoxville

Mathew Boehm, Ph.D. Student, Department of Geography, University of Tennessee-Knoxville

Morgan Douglas, M.S. Student, Department of Earth and Ocean Sciences, University of North Carolina Wilmington

Krysden Schantz, M.S. Student, Department of Earth and Ocean Sciences, University of North Carolina Wilmington

Elizabeth Yanuskiewicz, M.S. Student, Department of Earth and Ocean Sciences, University of North Carolina Wilmington

Elizabeth MacLennan, M.S. Student, Departmetn of Geography, University of Tennessee-Knoxville

Undergraduate Research Assistants:

Luke R. Blentlinger, Department of Geography, University of Tennessee-Knoxville

Eric Collins, Department of Geography, University of Tennessee-Knoxville

Julie Coulombe, Department of Geography, University of Tennessee-Knoxville

Akhil Gosai, Department of Geography, University of Tennessee-Knoxville

Allen Prince,  Department of Geography, University of Tennessee-Knoxville

Emma Reed,  Department of Geography, University of Tennessee-Knoxville

Trell Stroud,  Department of Geography, University of Tennessee-Knoxville

Wesleigh Wright,  Department of Geography, University of Tennessee-Knoxville

Bonnie Williams, Department of Earth and Ocean Sciences, University of North Carolina Wilmington

Audrey K. Taylor, Department of Earth and Ocean Sciences, University of North Carolina Wilmington (Currently Ph.D. student at the University of Notre Dame)

Publications Related to this Project:

Horn, S. P., Johanson, E. N., Haberyan, K. A., Boehm, M. S., Johanson, J. L., Sánchez P., M., and Hernández V., M. 2018. Initial Limnological Observations at Five Small Lakes in Southern Pacific Costa Rica. Cuadernos de Investigación UNED / UNED Research Journal 10(1): 119–134.

Horn, S.P. and Haberyan, K.A. 2016. Lakes of Costa Rica. Pp. 656–682 in Kappelle, M. (Ed.), Costa Rican Ecosystems. Chicago: The University of Chicago Press.

Lane, C.S., Horn, S.P., Taylor, Z.P., and Kerr, M.T. 2016. Correlation of Bulk Sedimentary and Compound-Specific δ13C Values Indicate Minimal Pre-Aging of n-Alkanes in a Small Tropical Watershed. Quaternary Science Reviews 145: 238–242.

Lane, C.S., S.P. Horn, and M. Kerr. 2014. Beyond the Mayan Lowlands: Impacts of the Terminal Classic Drought in the Caribbean Antilles. Quaternary Science Reviews 86: 89–98.

Lane C.S., and S.P. Horn. 2013. Terrestrially derived n-Alkane δD evidence of shifting paleohydrology in highland Costa Rica. Journal of Arctic, Antarctic, and Alpine Research 45: 342–349.

Presentations Related to this Project:

Johanson, E.N., M.T. Kerr, S.P. Horn, L.R. Blentlinger, and C.S. Lane, 2019. A 4,200-year record of fire history from the southern Pacific Costa Rica lowlands. Presented at the Annual Meeting of the American Association of Geographers, Washington, D.C.

Horn, S.P., M.S. Boehm, M.T. Kerr, E. Reed, W. Wright, C.S. Lane, M. Arford, and J. Graham, 2019. New proxy analyses from Laguna Martinez, Costa Rica. Presented at the Annual Meeting of the American Association of Geographers, Washington, D.C.

Kerr, M.T., S.P. Horn, and C.S. Lane, 2019. A revised chronology of paleohydrology and vegetation change at Laguna Bonillita, Costa Rica. Presented at the Annual Meeting of the American Association of Geographers, Washington, D.C.

Yanuskiewicz, E., C.S. Lane, E. Johanson, M.T. Kerr, and S.P. Horn, 2019. Compound-specific stable carbon isotope analysis of vegetation and land-use change at Laguna Los Mangos, Costa Rica. Presented at the Annual Meeting of the American Association of Geographers, Washington, D.C.

Blentlinger, L.R., S.P. Horn, M.T. Kerr, and C.S. Lane, 2018. Hydrogen isotope analysis of n-alkanes in sediments of Emerald Pond, Abaco Island, The Bahamas. Presented at the Annual Meeting of the Southeastern Division of the American Association of Geographers, Johnson City, TN.

Kerr, M.T., S.P. Horn, and C.S. Lane, 2018. Sedimentary nitrogen as a proxy for prehistoric forest clearance and site abandonment in southern Pacific Costa Rica. Presented at the Annual Meeting of the Southeastern Division of the American Association of Geographers, Johnson City, TN.

Kerr, M.T., Horn, S.P., and Lane, C.S. 2018. A 10,000 Year Hydrogen Isotope Record of Precipitation Variability from Highland Costa Rica. Paper to be presented at the annual meeting of the American Association of Geographers, New Orleans, Louisiana.

MacLennan, E., Horn, S.P., Kerr, M.T., Lane, C.S., and Ellis, K. 2018. A Compound-Specific Hydrogen Isotope Record of Precipitation from Coastal North Hispaniola.” Paper to be presented at the annual meeting of the American Association of Geographers, New Orleans, Louisiana.

Horn, S.P., Johanson, E.N., Haberyan, K.A., Boehm, M.S., Johanson, J.L., Sánchez P., M., and Hernández V., M. 2018. Limnological Observations at Five Costa Rican Lakes. Presented at the 3rd Biennial Geography Symposium: Mapping Outside the Lines: Geography as a Nexus for Interdisciplinary and Collaborative Research, 15–16 February 2018, Knoxville, Tennessee.

Blentlinger, L., and Horn, S.P. 2018. Experiments with Magnetic Susceptibility. Poster presented at the 3rd Biennial Geography Symposium: Mapping Outside the Lines: Geography as a Nexus for Interdisciplinary and Collaborative Research, 15–16 February 2018, Knoxville, Tennessee.

Collins, E., and Horn, S.P. Comparing Size Measurements of Prehistoric Maize Pollen Grains in Costa Rica and the Dominican Republic. 2018. Poster presented at the 3rd Biennial Geography Symposium: Mapping Outside the Lines: Geography as a Nexus for Interdisciplinary and Collaborative Research, 15–16 February 2018, Knoxville, Tennessee.

Johanson, E.N., S.P. Horn, C.S. Lane, and J.A. Cecil, 2018.  Fire history across the Little Ice Age in southern Pacific Costa Rica.  Presented at the Annual Meeting of the American Association of Geographers, New Orleans, LA.

Blentlinger, L.R., S.P. Horn, E.N. Johanson, M.T. Kerr, C.S. Lane, M.S. Boehm, and J.A. Cecil, 2017.  Proxy analyses of wetland sediments in Costa Rica.  Presented at the Annual Meeting of the Southeastern Division of the American Association of Geographers, Starkville, MS.

Blentlinger, L.R., S.P. Horn, E.N. Johanson, M.T. Kerr, J.A. Cecil, C.S. Lane, and M.S. Boehm, 2017.  Reconstructing past environments in Costa Rica through analyses of wetland sediments.  Presented at the University of Tennessee Discovery Day, Knoxville, TN.

Taylor, Z.P., C.S. Lane, and S.P. Horn, 2017. Hydrogen isotope evidence of climatic control on prehistoric agricultural activity in southern  Costa Rica.   Presented at the Annual Meeting of the Association of American Geographers, Boston, MA.

Johanson, E.N., S.P. Horn, and C.S. Lane, 2017.  Pre-Columbian agriculture, fire, and Spanish contact: A 4300-year record from Laguna Los Mangos, Costa Rica. Presented at the Annual Meeting of the Association of American Geographers, Boston, MA.

Kerr, M.T., C.S. Lane, and S.P. Horn, 2017.  Compound-specific stable hydrogen isotope (δD) analysis of lake-sediment cores: A key method for reconstructing prehistoric droughts and effects.  Presented at the XI Congreso de Antropologia, San Jose, Costa Rica.

Horn, S.P., C.S. Lane, E.N. Johanson, M. Sanchez, Z.P. Taylor, and M.T. Kerr, 2017.  Stable carbon isotope ratios in Costa Rican lake sediments as a proxy for forest clearance and crop cultivation.  Presented at the XI Congreso de Antropologia, San Jose, Costa Rica, San Jose, Costa Rica.

Horn, S.P., M. Sánchez, C.S. Lane, Z. Taylor, M.T. Kerr, Johanson, E.N., and J. A. Cecil, 2016.  Late Holocene fires in Costa Rica: Patterns and drivers.  Presented at the Annual Meeting of the Association of American Geographers, San Francisco, CA.

Kerr, M.T., S.P. Horn, and C.S. Lane, 2016.  Precipitation variability over the past 2500 years at Laguna Bonillita, Costa Rica.  Presented at the Annual Meeting of the Association of American Geographers, San Francisco, CA.

Johanson, E.N., S.P. Horn, and C.S. Lane, 2016.  A 4000-year record of paleoenvironmental change and agriculture intensification from Laguna Los Mangos in southern Pacific Costa Rica.  Presented at the Annual Meeting of the Association of American Geographers, San Francisco, CA.

Johanson, E.N., S.P. Horn, and C.S. Lane, 2015.  Late Holocene paleoenvironments and human-environment interactions from southern pacific Costa Rica: Two new records.  Presented at the Annual Meeting of the Association of American Geographers, Chicago, IL.

Outreach Efforts Related to this Project:

University of Tennessee Summer "Kids U" Course on Climate Change and Human Society

At the University of Tennessee, GRA Matthew Kerr shared research on climate change and humans with high school students in a summer course he developed on the ‘Collapse of Civilizations,’ which he taught for the 4th time in 2017 through UT's 'Kid's U' summer program.

University of Tennessee 'Mastodon Matrix' Workshop for Teachers

In December 2017, Horn, Kerr, and GRA Mathew Boehm partnered with the Tennessee Geographic Alliance to conduct a 'Mastodon Matrix' workshop for K-8 teachers on using encasing sediment from mastodon excavations for hands-on teaching about fossils and paleoenvironmental change. The workshop used material donated to Horn by the Paleoentological Research Institution in New York, and teachers took home 'goody bags' of mastodon matrix to use with their students, along with plastic plates and other supplies, ideas, and experience. Teachers were enthusiastic about the workshop and the hands-on opportunities of the mastodon matrix.

Oceans 17 Program for High School Juniors and Seniors (UNCW)

In the summer of 2017, two groups of 15 high school juniors and seniors participating in the Marinequest Oceans 17 summer education program at the UNCW Center for Marine Science conducted two-day mini projects in the UNCW stable isotope facility under the supervision of Co-PI Lane where they analyzed the bulk isotopic composition of flora and fauna collected along salinity gradients to observe the impacts of salinity on vegetation distributions and to establish trophic relationships between marine organisms based on stable nitrogen isotope analyses. During these camps, Lane gave 2-hour lectures on stable isotope applications in biological and geological research, including an introduction to compound-specific hydrogen isotope analyses and their application to paleoclimate reconstructions.  Once the students began hands-on bulk isotopic analyses in the stable isotope lab, Lane worked individually with 2-3 student groups/teams touring them through the hardware and operation of the GC-IRMS system as they awaited their bulk isotope results.  During this process, students were asked to formulate ideas for the types of research questions they might be able to answer using the compound-specific approach if they had adequate time and materials for compound isolation and analysis that might not be possible to answer using only bulk organic materials.