David T. Wang
GRADUATE STUDENT · MIT/WHOI · GEOCHEMISTRY

Hi! Thanks for stopping by.

I am a third-year Ph.D. student in the MIT/WHOI Joint Program. I work with Shuhei Ono in the Hardcore Stable Isotope Laboratory at MIT.

My research centers on the development of geochemical tools and technologies for understanding crustal processes, and is motivated by applications to natural resource exploration, Earth history reconstruction, and environmental remediation. As part of the effort to expand the frontiers of isotope geochemistry, I contribute to ongoing advancements in high-precision analytical instrumentation.

My abbreviated CV is here.

research

You can read about my current and past projects below. These projects generally involve characterizing the geochemical behavior of fluids and rocks in crustal environments. The end-goals are to develop methods to predict occurrences of important compounds at depth, and to interpret the imprint of geological processes through time & space.

NATURAL GAS GENERATION AND ALTERATION

The majority of my current research involves development of high-precision isotope analytical technologies and application towards understanding the generation and alteration of natural gases. I will post more details as they become available in the literature.

ISOTOPIC SIGNATURES OF MICROBIAL SULFATE REDUCTION

This project aims to understand biochemical controls on sulfur isotope signatures in the rock record.

The global cycles of carbon and sulfur are closely linked through biogeochemical processes occuring at a large range of spatial and temporal scales. Geochemists use subtle differences in atomic weight ("isotope fractionation") between crustal reservoirs of sulfur to infer past changes in the global carbon budget. Here at MIT, we want to understand how environmental and biological factors influence the magnitude of the fractionation. This knowledge enables us to more accurately interpret sulfur isotope signatures preserved in sedimentary rocks. Working with Shuhei Ono and Tanja Bosak, I am testing the hypothesis that sulfate-reducing bacteria will fractionate sulfur isotopes differently (and consistently so) depending on the quality of organic matter available to them.

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INTERNATIONAL GEOBIOLOGY COURSE / STROMATOLITES

I participated in the 2013 International GeoBiology Summer Course. Thanks to the folks at the Agouron Institute and other funding agencies for supporting this program.

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With faculty and other students on the course, I spent a few weeks studying stromatolites. Stromatolites are layered sedimentary structures that formed by accreting material from their environment. The layers can record information about changes in the waters in which the stromatolite was growing. We micro-drilled stromatolite from the Green River Formation for isotopic and elemental analyses, and modeled the variations between layers to infer large-scale changes in the hydrology of Lake Gosiute during the Eocene.

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TRACE METALS, PROTEOMICS, AND MARINE HETEROTROPHY

With Mak Saito at WHOI, I performed experiments on marine heterotrophic bacteria to better understand how rates of organic matter degradation in the oceanic water column may be affected by the availability of micronutrients. Certain elements (zinc, for example) are essential cofactors for enzymes used to break down organic matter. These metals are extremely scarce in certain regions of the ocean, so biological activity could be limited by their availability. Understanding the links between trace elements and the carbon budget better illuminates how marine systems are affected by perturbations to global element fluxes.

Towards that end, I participated in "Metzyme", a month-long research expedition aboard the R/V Kilo Moana. We transected the equatorial Pacific from Hawaii to Samoa to collect a full-depth trace metal and metaproteome profile. These samples help us determine how micronutrient availability affects biochemistry. Here are some photos from Metzyme.

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ISOTOPES AS TRACERS OF HEXAVALENT CHROMIUM CONTAMINATION

In 2010, I began working with Andre Ellis to develop chromium stable isotopes as tracers of chromium contamination in groundwater. In a study presented at AGU, we measured isotopic fractionation during the oxidation of chromium(III) to (VI) by environmentally-prevalent manganese oxides. Tracking chromium's stable isotopes is a promising new approach to monitoring remediation of chromium(VI) spills. Hexavalent chromium ("hex chrome") is more mobile and toxic than chromium(III), and as such, we studied how the stable isotopic composition of chromium might tell us about the redox behavior of chromium in contaminated groundwater. We found that oxidative processes impart isotopic fractionations that differ from reductive processes. These findings are promising for the application of chromium isotopes in monitoring remediation of contaminated sites.

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MOLECULAR BIOLOGY OF OVARIAN CANCER

I studied ovarian cancer cells with Oliver Dorigo and Chintda Santiskulvong at UCLA as a summer intern through the Amgen Scholars Program. In the Dorigo lab, I worked to characterize the regulation of cellular resistance to cisplatin, a platinum-based chemotherapy agent. By understanding how tumors become resistant to drugs like cisplatin, we can overcome a major obstacle to the long-term effectiveness of chemotherapy. I performed gene expression profiling on various strains of tumor cells to identify potential culprits involved in drug-resistance, and then characterized one of the biomolecules I identified, the insulin-like growth factor 1 receptor, in depth for its potential role in cisplatin resistance. Examples of the data generated are shown below.

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publications + presentations

PUBLICATIONS

  1. Sim MS, Wang DT, Zane GM, Wall JD, Bosak T, and Ono S (2013) Fractionation of sulfur isotopes by Desulfovibrio vulgaris mutants lacking hydrogenases or type I tetraheme cytochrome c3. Frontiers in Microbiology 4:171. // PDF // doi:10.3389/fmicb.2013.00171

POSTERS & TALKS

Name in bold on presentations for which I was presenting author.

  1. Corsetti et al., (including Wang). 2013 AGU. Clumped isotopes, trace elements, and δ18O of stromatolites from the Laney Member of the Green River Formation (Eocene): Implications for paleoenvironments during the Eocene Climatic Optimum. (poster)
  2. Metzger et al., (including Wang). 2013 AGU. Biogeochemistry of Stinking Springs, UT -- Part I: Inorganic carbon dynamics and constraints on nutrient fluxes in a warm, salty, sulfidic spring. (poster)
  3. Petryshyn et al., (including Wang). 2013 GSA. Grain trapping in stromatolites: Implications for stromatolite-building communities. (poster) link
  4. Ellis et al., (including Wang). 2012 ISEG. Cr stable isotopes and monitoring fate and transport of chromium—A review.
  5. Joshi, Wang, Ellis, Johnson, and Bullen. 2011 AGU. Stable isotope fractionation during chromium(III) oxidation by manganese oxides. (poster) link
  6. Wang, Fregoso, Ellis, Johnson, and Bullen. 2011 CSULA Student Symposium. Fractionation of chromium stable isotopes during oxidation by manganese oxides. (poster)
  7. Wang, Fregoso, Ellis, Johnson, and Bullen. 2010 AGU. Stable isotope fractionation during chromium(III) oxidation by δ-MnO2. (poster) link
  8. Wang, Santiskulvong, and Dorigo. 2010 UCLA Summer Research Program. Role of the insulin-like growth factor 1 receptor in cisplatin resistance in ovarian cancer. (poster)