• journal_title：Environmental Geosciences
• Contributor：Martin Zimmer ; Peter Pilz ; Jörg Erzinger
• Publisher：American Association of Petroleum Geologists (AAPG)
• Date：2011-
• Format：text/html
• Language：en
• Identifier：10.1306/eg.11181010017
• journal_abbrev：Environmental Geosciences
• issn：1075-9565
• volume：18
• issue：2
• firstpage：119
• section：ARTICLES

Subsurface geologic storage of carbon dioxide calls for sophisticated monitoring tools with respect to long-term safety and environmental impact issues. Despite extensive research, many factors governing the fate of injected carbon dioxide (CO₂) remain unclear. To identify possible risks through leakage of the CO₂ storage reservoir, a program for monitoring of the CO₂ flux at the surface was started at the Ketzin test site, which allows to distinguish between natural temporal and spatial flux variations and a potential leakage.

To gain adequate long-term baseline data on the local background CO₂ flux variations, CO₂ soil gas flux, soil moisture, and temperature measurements were conducted once a month during a 6-yr period. Furthermore, soil samples were analyzed for their organic carbon and total nitrogen contents.

The mean flux of all sampling sites before the CO₂ injection (2005–2007) was 2.8 μmol m⁻² s⁻¹ (ranging from 2.4 to 3.5), with a Q₁₀ factor of 2.4, and in the years after commencing injection (2009–2010), 2.4 μmol m⁻² s⁻¹ (ranging from 2.2 to 2.5), with the same Q₁₀ factor. The CO₂ flux rate is mainly controlled by the soil temperature. A significant influence of diurnal temperature variation and soil moisture was not detected. The spatial variability of the CO₂ flux among the 20 sampling locations ranges from 1.0 to 4.5 μmol m⁻² s⁻¹, depending on the organic carbon and total nitrogen content of the soil.

Through comparison with the long-term measurements, unusual high CO₂ fluxes can theoretically be distinguished from natural variations.