Texas Tech University

Research Team

Matthew Siebecker
      Matthew G. Siebecker
Assistant Professor Applied Environmental Soil Chemistry
Department of Plant and Soil Science
Texas Tech University
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.
Taylor (TJ) Hyde
      Taylor J Hyde - MS (non-thesis) student
TJ is pursuing his Master's Degree via distance learning at Texas Tech. As a part of his degree, he is researching and writing a review paper on the problem of potassium availability in West Texas soils for cotton production. His review includes potassium extraction techniques, potassium speciation, potassium solubility and exchange, and some of the important economics that cotton has to the South Plains region.
 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.
Emma Schmidt
      Emma Schmidt - MS (thesis) student
Emma is pursuing her Master's Degree. She is researching potassium speciation in Texas High Plains soils using wet chemical extractions and X-ray absorption spectroscopy (XAS). Her work will help build an understanding of the potassium distribution in the Plains soils; as well as determine the effects different extractants have on residual potassium in the soils. This information will identify which species of potassium are extracted from the soil, which can be applied to agriculture to help determine why cotton plants are exhibiting potassium deficiency symptoms despite soil tests.
Kindall Brijalba
      Kindall Brijalba - Undergraduate
Kindall is a junior level undergraduate working towards a major in Chemistry and a minor in Plant and Soil Science. She is a member of the American Chemical Society, the Institute of Electrical and Electronics Engineers' Nuclear and Plasma Sciences Society and the Raider Aerospace Society.

Presently under the guidance of Dr. Siebecker, she is working on the reduction kinetics of polymeric, colloidal manganese oxides (MnO2) by dissolved organic carbon using UV-Vis spectroscopy. The MnO2 phases are nanoparticulate. Manganese oxides are some of the strongest oxidizing agents to naturally occur in ecosystems. They are involved in an array of biotic and abiotic reactions carried out in groundwater and soil compositions. The goal of this project is to better understand the impacts of manganese oxides on organic carbon cycling, which has implications for carbon sequestration in soils.
 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.