<p>CO<sub>2</sub> emissions from geological sources have been recognized as an important input to the global carbon cycle. In regions without active volcanism, mines provide an extraordinary opportunity to observe dynamics of geogenic degassing close to its source.</p><p>High temporal resolution of stable carbon isotopes allows to outline temporal and interdependent dynamics of geogenic CO<sub>2</sub> contributions. We present data from an active underground salt mine in central Germany that were collected on site with a field-deployed laser isotope spectrometer.</p><p>Throughout the 34-day measurement period, total CO<sub>2</sub> concentrations varied between 805 ppmV (5<sup>th</sup> percentile) and 1370 ppmV (95<sup>th</sup> percentile). With a 400 ppm atmospheric background concentration, an isotope mixing model enabled the separation of geogenic (16&#8211;27&#160;%) from highly dynamic contributions from anthropogenic CO<sub>2</sub>-sources (21&#8211;54&#160;%). The geogenic fraction was inversely correlated to established CO<sub>2</sub> concentrations that were driven by anthropogenic CO<sub>2</sub> emissions within the mine. This indicates gradient-driven diffusion along microcracks.</p><p>Read more about this work in our open access publication in Scientific Reports at: http://rdcu.be/cblTz</p>
Development of a Stable Carbon Isotopes Analysis Instrument Based on Tunable Diode Laser Absorption Spectroscopy
