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.
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.
Presenting my poster at AGU - one of 12,000+ posters
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 →
Difficult to breathe on beautiful mountainside roads
Anita’s inlet and Mt. Kangchenjunga
Power plant on the Ganges
A colorful, textured and tiered city
Bose Institute inlet tower
Gas tank transport to the site
Anita at her site
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 →
It’s my fourth year as a TA for our ‘Experimental Atmospheric Chemistry’ undergraduate and graduate course at MIT, and today we have loaded up the department’s van with nitric oxide (NO) and ozone (O3) monitors, a uv radiometer, and three particulate monitors (PM 10, 2.5, and 1.0 um). As part of the ‘Pollution Exposure’ unit, Continue reading →
This week I traveled up to Mt. Washington with this year’s EAPS FPOP (Freshman Pre-Orientation Program) Discover Earth, Atmosphere and Planetary Sciences: Extreme Weather & Climate. It’s the third time I’ve acted as a TA for the program by heading up the flora and fauna section, or what is now more commonly known as “Flora with Laura.”
Topic: Soil microorganisms dominate the fate of atmospheric molecular hydrogen (H2 ) and comprise an estimated 75-80% of its global sink. Recent work has linked atmospheric H2 uptake to a novel high-affinity [NiFe]-hydrogenase expressed in active Streptomyces sp. cells , and is perhaps not driven by abiotic hydrogenases as was previously thought. Consequently, atmospheric hydrogen may be a 60-85 Tg yr−1 energetic supplement to microbes in Earth’s uppermost soil horizon. 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.
The porcupine was first spotted in the fall during a lunch break at the Harvard Forest Environmental Measurement Site instrument shed. It continued to reside beneath the shed as was clearly evident by the snow tracks (or more like a trough) leading to a nearby chewed on balsam fir. I set up a crittercam to record the action, and have compiled a “best of” video of our porcupine waltzing through the snow…
We posted an advertisement looking for an undergraduate to fill our MIT Undergraduate Research Opportunity Position (UROP) for summer research as part of the Harvard Forest Summer Research Program. We are very happy to have Deepa Rao ’12 join our research efforts.
American Geophysical Union General Assembly, 2010 poster
AGU 2010 Poster – Chemical tracers in the upper atmosphere
Abstract: A rare glimpse into the chemical and dynamical evolution of the Arctic polar vortex is provided by a suite of in situ balloonborne measurements. A set of mesospheric tracers observed in the late vortex validate theoretical mesospheric chemical profiles, which is especially valuable for the case of mesospheric H2 . Early vortex mesospheric profiles are constructed to explain mixing in tracer-tracer space. Expanding a model to incorporate three mesotracers, H2 , CO, and SF6 , instead of only one, will increase our ability to constrain estimates of the amount of mesospheric air that descended to stratospheric altitudes by vortex end.