by KATHRYN CLARK | Jan 24, 2017 | Putting it Out There
I had a great conference, I networked, had job interviews, presented my postdoctoral work, and met with collaborators and most importantly I was immersed in new science expanding my knowledge in Critical Zone processes. The best thing I saw at AGU was the session on Critical Zone Science Union (U53A: The Critical Zone: Revealing the Structure, Function, and Evolution of Earth’s Living Skin). It took place on Friday afternoon, but was worth the wait. It was well attended and is available through AGU on-demand at: https://vts.inxpo.com/scripts/Server.nxp?LASCmd=AI:1;S:17;F:QP!14100&EventKey=201126&EventAttendeeKey=18768642&ShowKey=33780&EventScreenCaptureMode=NULL&RandomValue=1484073070905
There were several interesting talks in this union, but I will focus on just two. Bill Dietrich (UC Berkeley) and Steven Holbrook (University of Wisconsin) focused their talks on the deep critical zone. Bill, spoke about the need to define and locate the layer of fresh bedrock, as the reactions there strongly influence earth surface processes. He outlined various hillslope theories which could be utilised to map the bedrock surface underlying the landscape, which he referred to as the next topographic revolution. Then, Steven Holbrook, a geophysicist, presented some novel techniques to measure the depth to bedrock in the field. As well, he spoke about a model which was able to predict the depth to bedrock through surface observations, from a 2015 Science paper by St. Clair et al. (http://science.sciencemag.org/content/350/6260/534). As a critical zonist, with a speciality in earth surface processes, river biogeochemistry, and catchment hydrology, I found this topic quite interesting, because the behaviour at the surface that I measure is influenced by the deeper critical zone structure, thus gained a greater appreciation for the deep critical zone.
by tierram | Jan 20, 2017 | Putting it Out There
Last December I attended the AGU Fall Meeting. I presented preliminary data on correlated EGA thermograms and 13C NMR spectra, see https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/134661.
This project is an active collaboration with Johnathan Sanderman at the Woodshole Research Center, and Jeffrey Baldock at Commonwealth Scientific and Industrial Research Organisation (SCaRP). National-scale inventories typically include soil organic carbon (SOC) content, but not chemical composition or biogeochemical stability. While 13C NMR is highly effective for SOM characterization, it is typically too expensive and time consuming for use in large-scale SOC monitoring. Therefore, we seek to understand if analytical thermal analysis is a viable alternative to NMR. This project has involved analyzing 300 agricultural samples collected by SCaRP, which have been divided into four fractions: whole soil, coarse particulates (POM), untreated mineral associated (HUM), and hydrofluoric acid (HF)-treated HUM. All samples have been analyzed by DSC-EGA, but only the POM and HF-HUM fractions were analyzed by NMR. The thermal and NMR data were analyzed by PCA and overlain with 2D Shige software to ascertain positive and negative correlations (as well as the intensity of these correlations). I made 5 key points in my presentation:
- Molecular composition is only part of the story.
- This due to the fact that C stability depends on soil chemistry
- Because thermal analysis a measure of biogeochemical stability, it may have great utility in assessing soil C dynamics
- DSC-EGA, NMR correlation provides dense information on SOC composition, stability, and lability
- We found strong positive and negative correlations between the CO2 thermograms and NMR spectra using 2D Shige.
The audience was intrigued by our findings so far. Moving forward, I will explore how mineral associations and mineralogy impact thermal data. This will entail running correlations against the DSC data.
by weliz | Jan 16, 2017 | Putting it Out There
Photo credit: AGU
The best thing that I saw at the AGU 2016 Fall Meeting was the Sagan Lecture by Nathalie Cabrol entitled, “The co-evolution of life and environment and the astrobiological quest.” Like many earth scientists, I often fantasize about applying my current research extreme environments and even to other planets; asking what was the carbon cycle like on a living Mars and how might that organic material have been preserved? But what should we be looking for?
Nathalie’s talk was about asking what type of microbial life inhabited Mars based on past Martian environmental conditions, where on Mars that life might have been active, how long this life was active on the Martian surface, and where might that life have gone when Mars became increasingly uninhabitable (deeper into the subsurface?). The last three questions would point to the places that future missions should go in search of life.
As the role of microbes in carbon cycling in soils including its necromass input of organic matter to soils becomes increasingly important on Earth, this talk inspired me to think more about how environmental/physical stress might affect both necromass production and the physical and chemical stabilization of necromass in the soil.
~Liz Williams
by Alain | Nov 16, 2016 | Putting it Out There
We are a busy hive of activity and it shows in our contributions to the 2016 Fall Meeting of the American Geophysical Union (AGU). Here is the list of the oral and poster presentations of our lab group members:
Tierra – Oral: B31L-06 Soil organic matter composition from correlated thermal analysis and nuclear magnetic resonance data in Australian national inventory of agricultural soils (Wednesday, Dec 14, 9:15-09:30, Moscone West 2006)
Kathryn – Oral: B22A-05 Tropical river suspended load and solute dynamics in storms within an extreme drought, Luquillo Critical Zone Observatory, Puerto Rico (Tuesday, Dec 13, 11:20-11:35, Moscone West 2004)
Liz Coward – Poster: B41D-0457 Organomineral Complexation at the Nanoscale: Iron Speciation and Soil Carbon Stabilization (Thursday, Dec 15, 8:00-12:20, Moscone South Poster Hall)
Liz Williams – Oral: PP24B-01 Bulk Soil Organic Matter d2H as a Precipitation Proxy (Tuesday, Dec 13, 16:00-16:15, Moscone West 2012). Liz is also co-author on V33G-02 Hydrogen Isotopes in Amino Acids and Soils Offer New Potential to Study Complex Processes (Wednesday, Dec 14, 13:55-14:10, Moscone South 308)
Alain – Poster: B41D-0456 A thermal analysis based model to quantify centennially persistent organic carbon in temperate soils (Thursday, Dec 15, 8:00-12:20, Moscone South Poster Hall). Alain is also co-author on B22B-01 The Soil Carbon Paradigm Shift: Triangulating Theories, Measurements, and Models (Tuesday, Dec 13, 10:20-10:35, Moscone West 2008); B22B-05 Beyond clay – using selective extractions to improve predictions of soil carbon content (Tuesday, Dec 13, 11:20-11:35, Moscone West, 2008); B41D-0455 Representation of diffusion controlled carbon stabilization in reactive transport models (Thursday, Dec 15, 8:00-12:20, Moscone South Poster Hall); B41D-0467 Digging a Little Deeper: Microbial Communities, Molecular Composition and Soil Organic Matter Turnover along Tropical Forest Soil Depth Profiles (Thursday, Dec 15, 8:00-12:20, Moscone South Poster Hall)
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