Nitrogen Gas Emissions from Shale Critical Zone Environments

Description

The weathering of nitrogen from shale bedrock has been recognized as an important component of the global nitrogen cycle. However the fate of this nitrogen remains largely uncharacterized. Mass balance considerations of global shale denudation rates and nitrogen concentrations suggest that shale weathering accounts for up to 25% of global unmanaged nitrogen inputs to the terrestrial environment. Crucially, due to an abundance of electron donors such as organic matter and sulfide minerals, shale bedrock environments may act as denitrification hotspots. The release of gaseous N2 (inert) and N2O (strong greenhouse gas), to the atmosphere. We will work towards quantifying the role of shale environments as a global source of N2O is therefore vital to (1) predicting the response and potential amplifying feedbacks of shale denitrification to a warming climate; (2) understanding natural drivers of climate variations in the past.To address this critical knowledge gap, we propose to study the conditions that promote N2 and N2O production and atmospheric efflux within the Mancos shale critical zone in the East River watershed. Ultimately we will characterize the environmental variables that promote the release of N2O relative to N2. To accomplish this, we will use a combination of field observations and laboratory incubations to determine the roles of moisture saturation, oxygen availability, and microbial function in driving observed N2O yields.