Assessing the Influence of Mineral Surface Chemistry on Soil Organic Matter Stability in the US in Response to Climate Change

Monday, 15 December 2014
Alexandra Toledo, Organization Not Listed, Washington, DC, United States, Katherine Heckman, US Department of Agriculture, Livermore, CA, United States, Craig Rasmussen, University of Arizona, Tucson, AZ, United States, Jennifer W Harden, USGS California Water Science Center Menlo Park, Menlo Park, CA, United States, Mark Johnson, US EPA, National Health and Environmental Effects Research Laboratory, Corvallis, OR, United States and Christopher Swanston, USDA Forest Service, Houghton, MI, United States
Soils represent a significant pool for carbon storage and sequestration. Previous field experiments have indicated that some mineral compositions are more effective in preserving soil organic matter (SOM) from microbial degradation. Due to climate change, it is important to quantify which soil types are changing in mineral surface chemistry. One way to do that is by differentiating the SOM stabilization mechanisms in different soil types at various depths. This study focused on examining the distribution of soil mass and composition by the soils density and mineral classification and the soils stability by measuring the amount of carbon and radiocarbon abundance. The United States Geological Survey collected the soils in Oregon, Mississippi, Alaska, and Arizona. The four different soil types were separated by density using density fractionation. Radiocarbon analysis of the different soils varying in density was conducted at Lawrence Livermore National Lab-Center for Accelerator Mass Spectrometry to determine the 13C/14C ratios. The ratios were used to determine the average age of the carbon in the samples. To determine the composition of the soil types, the soils were processed at Lawrence Berkeley National Lab using Fourier Transform Infrared-Attenuated Total Reflection. Results confirmed the amount of carbon, radiocarbon abundance and composition varied among the sites, thus SOM responds differently to climate change depending on the soil type.