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Manuscript presenting first yearlong study of carbonyl sulfide fluxes
Our manuscript on the “Seasonal fluxes of carbonyl sulfide in a midlatitude forest” was just recently published in PNAS (document online). Lead author Róisín Commane and I met at Harvard Forest where she installed an Aerodyne Research Inc., laser spectrometer to study the seasonal behavior of carbonyl sulfide (interchangeably called OCS and COS by different groups). Of particular interest are the common pathways to both CO2 and OCS, for example both trace gases react with carbonic anhydrase enzymes in leaves. This commonality may provide a quantitative, independent measure of the photosynthetic pathway for carbon assimilation. In this study, we find that vegetative uptake accounted for 72% of annual uptake of OCS, and nighttime uptake through stomata and…
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Manuscript evaluating a suite of flux-gradient methods for determining ecosystem H2 fluxes
A manuscript I’ve been working on entitled “Ecosystem fluxes of hydrogen: a comparison of flux-gradient methods,” was now been published in Atmospheric Measurement Techniques (view paper online). Our goal was to present a detailed experimental approach for measuring ecosystem fluxes of H2 and to test different so-called “flux-gradient methods” for calculating the H2 fluxes. Some common trace gas flux methods, e.g. eddy covariance, are not available for species like H2 that cannot be measured precisely at high frequencies (<1 Hz). We hope this paper will help inform the design of future studies for which flux-gradient methods might be the best option for measuring trace gas fluxes. Here are a couple…
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BioDesign course – bridging science and art
Biologist/architect team Tobi Lyn Schmidt and Mike Bogan created a course linking artists, designers, architects, and biologists from the California College of the Arts (CCA) and Stanford University. I served as a postdoc mentor to help inspire and guide the process of cross-hybridizing biology and design (some examples) with three really talented undergraduate CCA students: Leslie Greene, Sakurako Gibo, and David Lee. The students were first charged with creating designs to illustrate scientific concepts in my field of research. I challenged them think about the issue of scale with respect to the biogeochemical cycles I study. The processes I investigate occur over a wide range of spatial and temporal scales,…
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Manuscript linking consumption of atmospheric H2 to the life cycle of soil-dwelling actinobacteria
Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2). In Meredith et al. (2014) in Environmental Microbiology Reports, we probe the advantage of atmospheric H2 consumption to microbes and relationship between environmental conditions, physiology of soil microbes, and H2. First, we were interested in whether environmental isolates and culture collection strains with the genetic potential for atmospheric H2 uptake (a specific NiFe-hydrogenase gene) actually exhibit atmospheric H2 uptake. To expand the library of atmospheric H2-oxidizing bacteria, we quantify H2 uptake rates by novel Streptomyces soil isolates that contain the hhyL and by three previously isolated and sequenced strains of actinobacteria whose hhyL sequences span the known hhyL diversity. Second, we…
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Thesis Defense!
I defended my thesis entitled “Field Measurement of the Fate of Atmospheric H2 in a Forest Environment: from Canopy to Soil”. I was honored to receive the 2012 Carl-Gustaf Rossby Prize for my thesis (link to .pdf). It was an incredible feeling to defend. I really enjoyed preparing and giving my thesis defense presentation. It’s not often that one gets to present the culmination of six years of hard work and personal development to colleagues, family, and friends. I am grateful for mentorship from my advisor Ron Prinn, my thesis committee (Steve Wofsy – Harvard, Bill Munger – Harvard, Tanja Bosak – MIT, Colleen Hansel – WHOI, Shuhei Ono – MIT), and…
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Deepa receives Goetze Prize for Undergraduate Research
At the 2012 EAPS Student Awards Ceremony Deepa Rao received the Christopher Goetze Prize for Undergraduate Research for her thesis entitled : “Exploring the Microbe-mediated Soil H2 sink: A lab-based study of the physiology and related H2 consumption of isolates from the Harvard Forest LTER.” The award recognizes ” innovative experimental design, care in data collection, and sensitive application of results to research problems.” It has been a pleasure to supervise Deepa’s thesis research and her results will contribute to our research efforts to understand the mechanisms driving the soil sink for atmospheric H2. Professor Ron Prinn acts as the faculty advisor for both Deepa and I.
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Spotlight on H2 fluxes at Harvard Forest
PAOC Spotlight: Back to the forest Interview Micro-organisms have produced dramatic shifts in the composition of the Earth’s atmosphere and continue to be important drivers of ocean- and land-atmosphere exchanges of gases that have a strong influence on atmospheric composition and climate. An interesting example is the microbial influence on atmospheric molecular hydrogen (H2), which dominates the fate of this gas in the atmosphere. H2 is emitted to the atmosphere by about half natural and half anthropogenic, or human-induced, processes but it is predominantly removed from the atmosphere by microorganisms in the soil, which makes this process the most important, yet least understood, player in the atmospheric H2 budget. The MIT Program in…
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I survived the AGU 2011 Fall meeting
I just returned to Boston after the six weeks of travelling. My two weeks in California, filled with conferences and colleagues, was quite different from the intensive and somewhat isolated period spent in India. First stop was San Diego, where I attended the 44th Meeting of Advanced Global Atmospheric Gases Experiment (AGAGE) Scientists and Cooperating Networks at the Scripps Institute of Oceanography in La Jolla. Anita Ganesan’s instrument in Darjeeling may pave the way for the first AGAGE site in India, so the crowd was eager to hear her describe our success in deploying her instrument. Her dedicated and diligent work is paying off as she is collecting some of…
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Instrument deployment at Harvard Forest
After over a year of designing, building, and testing a custom instrument system to measure fluxes of molecular hydrogen (H2), I deployed the system to the Harvard Forest Long Term Ecological Research site in Petersham, Massachusetts (http://harvardforest.fas.harvard.edu/). With the instrument installed, I will measure hydrogen fluxes for a year to determine the seasonal dynamics of H2 cycling in this mixed deciduous forest, and in particular, to characterize the strong soil sink for atmospheric H2. The instrument shed was tight, and I was packing a lot of equipment. But the move in day was a successful and fun experience thanks to the help of colleagues at Harvard University. This short documentary created by fellow PhD student Ryan Abernathey…