2010 GSA Denver Annual Meeting (31 October –3 November 2010)
Paper No. 62-12
Presentation Time: 5:05 PM-5:20 PM


BURCHELL, Alison, NTS Group, Box 3671, Boulder, CO 80307, a_burchell@comcast.net, YAGER, Douglas B., Mineral Resources Program, U.S. Geological Survey, P,O. Box 25046, MS 973, Denver Federal Center, Denver, CO 80225, USA USA, JOHNSON, Raymond H., S.M. Stoller Corporation, Contractor to the Department of Energy Office of Legacy Management, 2597 Legacy Way, Grand Junction, CO 81503, AIKEN, George R., US Geological Survey, WRD, 3215 Marine St, Marine Street Science Center, Boulder, CO 80303, and BUTLER, Kenna, U.S. Geological Survey, WRD, 3215 Marine Street, Suite E-127, Marine Street Science Center, Boulder, CO 80303

The need to reduce CO2 levels has stimulated studies to better understand and quantify potential carbon sinks. Soils represent a significant natural terrestrial sink needed to mitigate rising atmospheric CO2. To examine NTS, TOSC stability and the potential for DOC as a climate change proxy, soil cores and water samples from high plains to alpine sites in non-wetland environments were analyzed.

Forest soils derived from intermediate to mafic volcanic bedrock that exhibit BC horizons have the highest TOSC (34.15 wt %), C: N (43) and arylsulfatase enzyme activities (EA) >278 µg p-nitrophenol/g/h). Monzonite, shale and gneiss terrain has intermediate TOSC. Unreclaimed mine sites have the lowest TOSC (0.01 wt %), C: N (0 – 6.5) and EA (0 - 41). In mineralized areas, naturally reclaimed and undisturbed soils derived from propylitized volcanic rock also exhibit high TOSC (13.5 - 25.6 wt %), C: N and EA. This is consistent with earlier studies in which propylitic bedrock was found to have a high, natural acid neutralizing capacity (ANC) as characterized by calcite-chlorite-epidote. Charcoal radiocarbon dates collected from paleo-burn horizons indicate an old and, if undisturbed, stable carbon pool (500 -5,440 yr B.P.). Peak runoff and low-flow samples from surface waters at monitored sites were analyzed for DOC. In general, DOC flux in undisturbed and natural reclaimed areas is low (ave.0.9 mg/L) –indicating that C is not readily released.

The resulting high NTS potential is attributed to: host-rock weathering nutrients, contaminant neutralization, formation of secondary mineral carbonates, formation of soil aggregates, high specific surface area and adsorption enhancing Ca-Mg-Fe clays that stabilize C and N, and BC horizons, which support soil development and cation exchange. The data suggest TOSC and DOC correlate with soil properties, bedrock geology and alteration type. Data from recovering burn areas and natural reclamation sites indicate biogeomimicry practices correlated with bedrock and site specific soil amendments including ANC rock and biochar can support ecosystem services such as soil productivity, moisture retention and erosion mitigation. Enhancing the NTS potential of soils may be a cost-effective strategy to help draw down atmospheric CO2 and restore forests, watersheds and disturbed lands.

2010 GSA Denver Annual Meeting (31 October –3 November 2010)
General Information for this Meeting
Session No. 62
Pyrogenic Black Carbon, or Biochar, in Soils and Sediments, Its Characterization and Fate—Its Effects On the Carbon Cycle and Carbon Sequestration, and Its Effects on Soil Properties
Colorado Convention Center: Room 601
1:30 PM-5:30 PM, Sunday, 31 October 2010

Geological Society of America Abstracts with Programs, Vol. 42, No. 5, p. 160

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