Zheng-Hua Li, PhD

Research Areas

Climate Change: In collaboration with Dr Steve Driese at Baylor University and Dr Sally Horn at UTK, I currently investigate high-resolution paleoclimate variability and seasonality in southeastern United States using complementary multiple paleoclimate proxies from various terrestrial archives including speleothems, tree rings, soil organic matter, and organic molecular compounds.  I particularly focus my interest on the paleoclimate reconstruction in certain time windows, e.g., middle Holocene Warm Period, the transition of the last glacial to Holocene, as well as abrupt climate events, e.g., the Y.D., the 8.2ka, and the climate-human interaction. A study has been carried out on δ¹³C, δ¹⁸O study on tree-ring a-cellulose on woodcell scale to investigate regional δ¹³C, δ¹⁸O seasonal patterns associated with regional precipitation patterns and climatic events. I also pursue quantitative reconstruction of paleoclimate history by analyzing stable C, O, H isotopic compositions of speleothems (including the “Clumped Isotopes”) from southern Appalachian region. In the past few years, I have received numbers of speleothems donated by local cave owners, which provide me a unique opportunity to reconstruct paleoenviromental history for this region. In collaboration with Dr Glenn Tootle in Department of Civil Environment and Engineering, UTK, I have initialized to use tree-ring isotopes (δ¹³C, δ¹⁸O and δ²H) to detect mountain glacial meltwater signals in  the Wind River Range of Wyoming (WRR) which hosts seven of the 10 largest glaciers in the continental United States. The recent recession and shrinking volume of WRR glaciers is alarming because of increased demands in human and ecological water supplies and the importance of glacier meltwater to this water supply. This study aims to understand climate change impacts on glacier volume variability and stream discharge, and assess the lifetime of these glacials. Mountain glacier sites within the WRR watershed provide the ideal natural settings to test the hypothesis by using stable isotope in tree rings to detect and distinguish glacier meltwater signals from meteorological parameters because of the occurrence of the maximum difference between the peak discharge of glacier meltwater and low seasonal precipitation in the latewood formation period. This novel approach is expected to improve our understanding of mountain glacial recessions in other regions around the world. The long-term tree-ring isotope time series established will provide insights on climate variability and climate events (e.g., Pacific Decadal Oscillation, El Nino-Southern Oscillation) in this region.

      Stable Isotope Forensics: Isotopic and elemental characteristics of human bone, teeth and hair have been demonstrated as useful biomarkers for forensic anthropologists and criminal investigators. These biomarkers trace locations and movements of the individuals and aid in the identification of human remains.  In collaboration with Dr. Nicholas Herrmann at Mississippi State University and my postdoc research associate Dr. Daniel Weinand at EPS, I have been conducting multiple isotopes (carbon, oxygen, hydrogen, and nitrogen) and trace elements study in modern human bone, teeth and hair from the William Bass Donated Skeletal Collection (WBDSC), the Maxwell Museum Documented Skeletal Collection and the Texas State University-San Marcos Forensic Research Facility. The WBDSC represents the largest modern osteological collection in the United States. The fulfillment of this project will generate a national isotope database derived from the WBDSC and the other donated skeletal collections; provide forensic anthropologists and criminal investigators a comparative database to trace locations and movements of the individuals and aid in the identification of human remains for forensic anthropologists and criminal investigators.

       Research Outreach: I have been actively involved in K-12 education to promote science awareness for our local community schools. I have worked with a numbers of local high school and middle teachers and students to carry out various science projects in the Stable Isotope Lab.

Federally Funded Research Projects (active)

Zheng-Hua Li (PI/PD), Steve G. Driese (co-PI), Sally P. Horn (co-PI): Pleistocene-Holocene climate variability of the southern Appalachian region, southeastern U.S. ($390,918, NSF, Oct.1, 2009-Sept.30, 2012)

Nicholas P. Herrmann (PI), Zheng-Hua Li (co-PI): Isotopic and elemental analysis of the William Bass Donated Skeletal Collection and other modern donated collections. ($687,424, NIJ, Jan.1, 2009-Dec.31, 2011)