Rapid Access: Justifying a Proposed Alteration of Chemical Composition of Soil-leached Dissolved Organic Matter in Sub-Arctic Soils
EMSL Project ID
49484
Abstract
Half of the global belowground organic carbon (OC) is stored in high-latitude frozen soils (permafrost). Temperatures have risen ~1 degrees C over the last 30 years (IPCC, 2013), which exposes substantial quantities of OC to decomposition by soil microbes and mobilization by surface runoff and groundwater. A lot of research on DOM in Arctic rivers have found the surface runoff carries mostly modern DOM from surface plant debris. As thaw depth increase in the high-latitude soils, mobilization of deeper old soils might change this result. Thus, understanding how DOM is transported and leaching effect of precipitation in soil is critically important with increased thawing of deep permafrost. Due to global climate change, the high-latitude frozen soils are vulnerable to mobilization and decomposition. As thaw depth increase in the high-latitude, a lot of old high organic soil are now frozen might thaw in the near future and be accessible to surface runoff. Although many studies have shown significant inputs of DOM from high-latitude soils to coastal systems via fluvial transport, the composition of dissolved organic matter (DOM) and the mobilization mechanism in soils are still unclear. To address this, we conducted a soil leaching experiment on upper and deeper soils from Alaska to understand the change in DOM concentration and composition during leaching and the role of deeper soil on DOM transport upon thawing. This leaching experiment showed a retention effect of organic rich deep soil from the high-latitude region on percolating DOC and preferential adsorption and desorption of certain compound classes. On a broader scale, it provides information on the composition of the organic matter that is mobilized from soil sources into rivers and lakes in the high-latitude region, which is relatively unconstrained compared to the studies on river transport of terrestrial OC to estuaries and coastal deposition in pan-Arctic region. As temperature raise in the pan-Arctic region, what we saw in this leaching experiment is expected to happen more frequently on a larger scale. Here we request assistance from the EMSL mass spectrometry facility to characterize the chemical compositions of upper and deeper soil leachates. This information will be compared with DOC, FDOM data we have to better understand the adsorption and desorption of chemical classes in deeper soil horizon. This work has important implications for understanding how carbon is mobilized in soils in a thawing Arctic which has strong linkages with what types of carbon remain stored or get converted to greenhouse gases in soils.
Project Details
Project type
Limited Scope
Start Date
2016-05-03
End Date
2016-07-03
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Hutchings, J., X. Zhang, T.S. Bianchi, E. Schuur, A.R. Arellano, and Y. Liu (2016), Effects of Enhanced Thaw Depth on the Composition of Arctic Soil Organic Matter Leachate, AGU Fall Meeting 2016, San Francisco, CA.
Zhang X, J Hutchings, TS Bianchi, Y Liu, A Arellano, and EA Schuur. 2017. "Importance of lateral flux and its percolation depth on organic carbon export in Arctic tundra soil: implications from a soil leaching experiment." Journal of Geophysical Research. Biogeosciences 122(4):796-810. doi:10.1002/2016JG003754