Texas Tech University

Research Team

Matthew Siebecker
      Dr. Matthew G. Siebecker
Assistant Professor Applied Environmental Soil Chemistry
Department of Plant and Soil Science
Texas Tech University
Aakriti Sharma
Dr. Aakriti Sharma - Postdoctoral Researcher
Aakriti Sharma is a postdoctoral research associate in the Department of Plant and Soil Sciences at Texas Tech University. Dr. Sharma received a PhD in Soil Science in 2019 from North Carolina State University in Raleigh, NC. Prior to joining Texas Tech, she worked as a Postdoc at NC State University. Her research interest centers around understanding the binding mechanisms of nutrients and contaminants in complex geochemical systems at multiple spatial scales. Her research extensively uses state-of-the-art techniques, especially synchrotron radiation-based techniques and electron microscopy, along with spatial statistical modeling. Currently, her research focuses on understanding at a molecular-scale why and how fast novel pathways of potassium fixation are occurring in soil clay mineral systems. 
Amanda Jo Zimmerman
      Amanda Jo Zimmerman - PhD student
Amanda Jo is pursuing her doctorate in environmental soil chemistry. Before returning to graduate school she worked for the Bureau of Ocean Energy Management as a geophysicist and for Delgado Community College teaching freshman geology. She is interested in pursuing a career in the United States Geological Survey (USGS), working to preserve our land.

Her current research project is analyzing geogenic arsenic speciation in soils from northwestern Costa Rica, specifically drinking water filter waste (titanium dioxide, TiO2) sediments deposited on the soil surface. The objective of this study is to identify the concentration of As in these soils as well as mobility with the objective to adequately quantify risk to local population. She relies on both wet chemical methods in the laboratory, such as desorption and bioavailability studies, as well has advanced synchrotron radiation-based techniques, such as X-ray absorption spectroscopy (XAS), including both the near edge (XANES) and extended fine structure (EXAFS) spectra.
 Cynthia Jordan
      Cynthia Jordan - MS (thesis) student
Cynthia is pursuing a master's degree in Plant and Soil Science with a concentration in Soil Science. She is co-advised by Drs. David Weindorf and Matthew Siebecker. During her time as the senior research technician, she advanced research initiatives to integrate multiple types of proximal sensors, such as portable X-ray fluorescence (PXRF), VisNIR, and the NixPro color sensor, into soil characterization. As a graduate student, Cynthia's research project involves soil visualization via core samples from southern Lamb County, TX, and northern Lubbock County, TX. The project's objectives include the collection of soil cores at variable spatial resolutions, acquirement of proximal sensor and traditional laboratory characterization, and development of a novel three-dimensional data visualization tool based upon soil core data (i.e., combining physical, chemical and color measurements). With the completion of this degree, Cynthia seeks to continue her studies in soil science to pursue a doctoral degree.
 Katherine Coyle
Katherine Coyle - Undergraduate
Katherine is a junior level undergraduate student in the College of Arts and Sciences working toward a bachelor's degree in Geoscience. She is a member of the Honors College and is an undergraduate research assistant under Dr. Siebecker. She began working in the Plant and Soil Sciences lab in January of 2021. Her academic interests include climate change, water management, and planetary geology.

Under the instruction of Dr. Siebecker, Katherine is working to better understand potassium fixation in newly formed minerals, particularly in West Texas soil. She is conducting adsorption experiments with varying concentrations and changing pH. She is utilizing the ICP-OES as well as techniques such as TEM, SEM, and XRD.
Danira Garcia Gutierrez
      Danira Garcia Gutierrez - Undergraduate
Danira is a second year undergraduate student in the College of Arts and Sciences. She is currently majoring in Biochemistry and minoring in both Biology and English. She is a member of the Honors College and an Undergraduate Research Scholar under the guidance of Dr. Siebecker. She began working in the Environmental Soil Chemistry Lab in the Spring of 2019. In the future, Danira hopes to enroll at the Texas Tech Health Sciences Center where she will study medicine.

With the direction of Dr. Siebecker, Danira is working on several projects. Her main study is on the mobility and speciation of arsenic in contaminated soils and sediments from northwestern Costa Rica. The soil and sediment samples have unusually high concentrations of the toxic, due to local water filtering techniques used to remove geogenic arsenic from drinking water. The focus of this project is to understand the effects of arsenic mobility in both urban and agricultural settings. She is conducting experiments using techniques such as Particle Size Analysis, X-ray diffraction, and scanning emission microscopy (SEM).
 Thanh Pham
Thanh Pham - Undergraduate
Thanh is a junior level undergraduate student. He majors in Chemical Engineering and minors in Bioengineering and Mathematics. He aims to pursue PhD and become a professor. Under the instruction of Dr. Siebecker, Thanh is working on potassium binding to soil and how minerals transform over time using different types of metal oxides and techniques such as: Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). This study helps improve soil health and crops production.
Alumni -  MS Thesis (current position)
Emma Schmidt (US Navy)
Alumni -  MS Non-thesis
Randy Riddle (USDA)
Taylor J Hyde (Montrose Marketing and Management)
Alumni -  Undergraduate (current position)
Kindall Brijalba (US Navy)