Changes in mineral stabilized soil organic carbon composition during pedogenesis
EMSL Project ID
48320
Abstract
A detailed study of carbon in soil chronosequences along the precipitation gradient of the west coast of the U.S. will quantify the mechanisms through which carbon is stabilized and show how stabilization of soil organic matter (SOM) changes with climate and time. We have sampled complete soil profiles on terraces of two chronosequences for total SOM and bulk soil 14 C age. At EMSL we will analyze the composition of dissolved organic carbon (DOC) in pore water and SOM of soils from the Santa Cruz chronosequence. This data will inform mechanistic models of soil organic matter transformations through time. Santa Cruz data will be compared with SOM composition of soil profiles from a wetter chronosequence at the mouth of the Mattole River in Northern California. The contrast in SOM of wet and dry soil chronosequences will provide insight into climatic controls on SOM stabilization. In addition, the Santa Cruz profiles will be investigated with respect to soil mottling and carbon sequestration. The wetter Mattole soils do not exhibit mottling. To improve mechanistic understanding of SOM, we will isolate different carbon-mineral associations through sequential extractions that dissolve minerals of varying crystallinity. The analytic capabilities of EMSL will allow detailed characterization of organic compounds associated with bulk soil and soil mineral separates. The data will substantially improve mechanistic understanding of carbon-mineral interactions through space and time. Project Details
Project type
Large-Scale EMSL Research
Start Date
2014-10-01
End Date
2016-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Related Publications
Garcia Arredondo M., C.R. Lawrence, M.S. Schulz, M.M. Tfaily, R.K. Kukkadapu, M.E. Jones, and K.E. Boye, et al. 2019. "Root-driven weathering impacts on mineral-organic associations in deep soils over pedogenic time scales." Geochimica et Cosmochimica Acta 263. PNNL-SA-137958. doi:10.1016/j.gca.2019.07.030