Bedrock weathering rates, reactive nitrogen influxes and effluxes, and nitrous oxide emissions rates from the Pumphouse Hillslope, East River Watershed, Colorado
- Lawrence Berkeley National Laboratory; Lawrence Berkeley National Laboratory
- Lawrence Berkeley National Laboratory
Atmospheric nitrous oxide contributes directly to global warming, yet models of the nitrogen cycle do not account for bedrock, the largest pool of terrestrial nitrogen, as a source of nitrous oxide. Although it is known that release rates of nitrogen from bedrock are large, there is an incomplete understanding of the connection between bedrock-hosted nitrogen and atmospheric nitrous oxide. Here, we quantify nitrogen fluxes and mass balances at a hillslope underlain by marine shale. We found that at this site bedrock weathering contributes 78% of the subsurface reactive nitrogen, while atmospheric sources (commonly regarded as the sole sources of reactive nitrogen in pristine environments) account for only the remaining 22%. About 56% of the total subsurface reactive nitrogen denitrifies, including 14% emitted as nitrous oxide. The remaining reactive nitrogen discharges in porewaters to a floodplain where additional denitrification likely occurs. We also found that the release of bedrock nitrogen occurs primarily within the zone of the seasonally fluctuating water table and suggest that the accumulation of nitrate in the vadoes zone, often attributed to fertilization and soil leaching, may also include contributions from weathered nitrogen-rich bedrock. Our hillslope study suggests that under oxygenated and moisture-rich conditions, weathering of deep, nitrogen-rich bedrock makes an important contribution to the nitrogen cycle. The data files are in Excel, which can be accessed using Microsoft Office, and consist of many data sets from the Pumphouse Hillslope PLM (Pumphouse Lower Montane) 1, 2, 3, and 4. They include soil to rock (0-10 meters) solid phase minerals and elements compositions; time- and depth-resolved pore-water chemistry and pore-gas compositions; time- and depth-resolved water table depths and water fluxes; subsurface weathering rates; nitrogen influxes and effluxes and mass balance. The attached paper is in a Word document, which can be accessed using Microsoft Office, and in pdf format.
- Research Organization:
- Environmental System Science Data Infrastructure for a Virtual Ecosystem; Watershed Function SFA
- Sponsoring Organization:
- U.S. DOE > Office of Science > Biological and Environmental Research (BER)
- OSTI ID:
- 1766328
- Report Number(s):
- paf_674
- Country of Publication:
- United States
- Language:
- English
Similar Records
Hillslope subsurface flow and transport data for the PLM transect in East River, Colorado
Data used in manuscript "Quantifying Subsurface Flow and Solute Transport in a Snowmelt-recharged Hillslope with Multiyear Water Balance", submitted to Water Resources Research on 5-26-2022
Related Subjects
Anion
Cation
Dissolved Ammonia
Dissolved Inorganic Carbon
Dissolved Organic Carbon
EARTH SCIENCE > LAND SURFACE > SOILS > HYDRAULIC CONDUCTIVITY
EARTH SCIENCE > TERRESTRIAL HYDROSPHERE > GROUND WATER > GROUNDWATER CHEMISTRY
Groundwater Flux
Groundwater Level
Mineralogy
Tensiometer Head
Total Dissolved Nitrogen
Total Nitrogen
Total Organic Carbon
bedrock weathering
nitrous oxide emissions
rock nitrogen
shale bedrock
subsurface reactive nitrogen
watershed hillslope