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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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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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Helping deploy Anita’s instrument to Darjeeling, India
Update: The first publication from Dr. Anita Ganesan’s work in Darjeeling has been published in Atmospheric Chemistry and Physics (view document online). I’m in my second week in India, where I am helping fellow Prinn-group graduate student Anita Ganesan deploy her gas chromatograph to Darjeeling, a town high on a ridge in West Bengal in the foothills of the Himalayas (Anita has a blog now!). It’s quite a trek to get to the Bose Institute where her instrument will be housed. We spent a few days adjusting to the change in time and culture in the hectic city of Kolkata. A haze hung over the city, making the day seem…
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MBL microbial diversity course
In the summer of 2010, I spent six inspiring, challenging, and chaotic weeks at the Marine Biological Laboratory Microbial Diversity Course in Woods Hole, MA. I hoped to take full advantage of the opportunity granted by course directors Steve Zinder and Dan Buckley of Cornell to plunge head on into the world of microbiology. I was eager to learn the theory and hands-on methods to study the microbial world, which has such a profound impact on atmospheric composition, and this course gave me a chance to explore my interests in a way not offered anywhere else.