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.
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.
In this video graduate student Laura Meredith shares her thesis work to build and deploy an instrument to the Harvard Forest Long Term Ecological Research site in central Massachusetts. Laura is in the Climate Physics and Chemistry Program. Her advisor is Ron Prinn.
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 the first high precision direct greenhouse gas measurements in India.
I gave a talk at the AGAGE meeting on my recent work on the flux of H2, CO2 and COS between the soil and atmosphere at Harvard Forest. I focus on the persistence of soil-atmosphere exchange of trace gases across snowpack, which insulates the soil microbial community from freezing air temperatures while allowing trace gases to diffuse through the porous snow matrix. I’m interested in how strongly the biogeochemical cycling continues throughout the winter and in comparing the behavior of the different cycles in the low temperature ‘incubator’ beneath the snow. Continue reading
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 darker and the nights lighter, and there was a constant smell of burning. It was not unpleasant, but the concerns about the impact of particulate levels on air quality and health that we are taught in the classroom were made real. Two million people in this city and its surroundings breathe this local atmosphere daily, until it is exported to the globe. Continue reading
Instrument installation is finally complete and things have been running smoothly through the fall and winter seasons. Here are some photos of the installation and current setup, and of the forest in general.
Two years after embarking on my thesis project to design and build a custom instrument that measures hydrogen fluxes, I deploy my creation to the Harvard Forest Long Term Ecological Research site in Petersham, Massachusetts. The instrument shed is tight, but with the help of colleagues at Harvard University, the move is successful. In this short documentary by co-student Ryan Abernathey we introduce the forest and the project, but the work has only just begun…