I am broadly interested in understanding natural systems on a molecular level, using both stable metal isotope fractionation and spectroscopy. I entered the department of Geological Sciences at Stanford University as a graduate student in fall 2014. I am currently working with Professors Kate Maher and Gordon Brown on developing a thermodynamic framework for kinetic stable isotope fractionation during redox processes and applying this framework to the reduction of chromium(VI), a common environmental pollutant, by aqueous iron(II) complexes and iron(II)-bearing clay minerals.
As an undergrad, I majored in chemistry at Princeton University and worked in the group of Geosciences Professor Satish Myneni, who sparked my interest in geochemistry. My research projects in the Myneni group included developing a method to quantify thiols in natural systems and characterizing halogenation of natural organic matter.
Honors & Awards
Stanford Graduate Fellowship, Stanford University (2014-2019)
National Defense Science and Engineering Graduate (NDSEG) Fellowship, Department of Defense (2014-2017)
Phi Beta Kappa Member, Phi Beta Kappa Society (2014)
Robert Thorton McCay Prize for Physical Chemistry, Princeton University (2014)
Sigma Xi Research Society Member, Sigma Xi Research Society (2014)
Shapiro Prize for Academic Excellence, Princeton University (2011-2012)
Education & Certifications
A.B., Princeton University, Chemistry, summa cum laude (2014)
Kinetics and Products of Chromium(VI) Reduction by Iron(II/III)-Bearing Clay Minerals
ENVIRONMENTAL SCIENCE & TECHNOLOGY
2017; 51 (17): 9817–25
Hexavalent chromium is a water-soluble pollutant, the mobility of which can be controlled by reduction of Cr(VI) to less soluble, environmentally benign Cr(III). Iron(II/III)-bearing clay minerals are widespread potential reductants of Cr(VI), but the kinetics and pathways of Cr(VI) reduction by such clay minerals are poorly understood. We reacted aqueous Cr(VI) with two abiotically reduced clay minerals: an Fe-poor montmorillonite and an Fe-rich nontronite. The effects of ionic strength, pH, total Fe content, and the fraction of reduced structural Fe(II) [Fe(II)/Fe(total)] were examined. The last variable had the largest effect on Cr(VI) reduction kinetics: for both clay minerals, the rate constant of Cr(VI) reduction varies by more than 3 orders of magnitude with Fe(II)/Fe(total) and is described by a linear free energy relationship. Under all conditions examined, Cr and Fe K-edge X-ray absorption near-edge structure spectra show that the main Cr-bearing product is a Cr(III)-hydroxide and that Fe remains in the clay structure after reacting with Cr(VI). This study helps to quantify our understanding of the kinetics of Cr(VI) reduction by Fe(II/III)-bearing clay minerals and may improve predictions of Cr(VI) behavior in subsurface environments.
View details for DOI 10.1021/acs.est.7b02934
View details for Web of Science ID 000410255800044
View details for PubMedID 28783317
- Element release and reaction-induced porosity alteration during shale-hydraulic fracturing fluid interactions APPLIED GEOCHEMISTRY 2017; 82: 47–62
- Impact of Organics and Carbonates on the Oxidation and Precipitation of Iron during Hydraulic Fracturing of Shale ENERGY & FUELS 2017; 31 (4): 3643-3658
Estimation of Reactive Thiol Concentrations in Dissolved Organic Matter and Bacterial Cell Membranes in Aquatic Systems
ENVIRONMENTAL SCIENCE & TECHNOLOGY
2012; 46 (18): 9854-9861
Organic thiols are highly reactive ligands and play an important role in the speciation of several metals and organic pollutants in the environment. Although small thiols can be isolated and their concentrations can be estimated using chromatographic and derivatization techniques, estimating concentrations of thiols associated with biomacromolecules and humic substances has been difficult. Here we present a fluorescence-spectroscopy-based method for estimating thiol concentrations in biomacromolecules and cell membranes using one of the soluble bromobimanes, monobromo(trimethylammonio)bimane (qBBr). The fluorescence of this molecule increases significantly when it binds to a thiol. The change in the sample fluorescence due to thiols reacting with qBBr is used to determine thiol concentration in a sample. Using this method, small thiols such as cysteine and glutathione can be detected in clean solutions down to ~50 nM without their separation and prior concentration. Thiols associated with dissolved organic matter (DOM) can be detected down to low micromolar concentration, depending on the DOM background fluorescence. The charge on qBBr prevents its rapid diffusion across cell membranes, so qBBr is ideal for estimating thiol concentration at the cell membrane-water interface. This method was successfully used to determine the thiol concentration on the cell envelope of intact Bacillus subtilis to nanomolar concentration without any special sample preparation. Among the chemical species tested for potential interferences (other reduced sulfides methionine and cystine, carboxylate, salt (MgCl(2))), carboxylates significantly influenced the absolute fluorescence signal of the thiol-qBBr complex. However, this does not affect the detection of thiols in heterogeneous mixtures using the presented method.
View details for DOI 10.1021/es301381n
View details for Web of Science ID 000308787800006
View details for PubMedID 22916681