Assessment of soil moisture influence on CO2 flux: a laboratory experiment

• Published in: Environmental earth sciences 2009-08, Vol.58 (3), p.491-497
• Main Authors: Sanci, Romina, Panarello, Héctor O., Ostera, Héctor A.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Climate change; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Emission measurements; Engineering and environment geology. Geothermics; Exact sciences and technology; Fluctuations; Geochemistry; Geology; Moisture content; Original Article; Pollution, environment geology; Sand; Sandy loam; Sandy soils; Soil moisture; Soils; Surficial geology
• ISSN: 0943-0105; 1866-6280; 1432-0495; 1866-6299
• DOI: 10.1007/s00254-008-1522-7

Accurate measurements to assess the influence of soil moisture on CO 2 flux requires the absolute estimates of soil CO 2 flux. Thus, it was constructed a calibration system where CO 2 with fixed concentration flowed through the different porous material. Previous to measurement, in order to verify the performance and reliability of a closed dynamic chamber, different discontinuous air-mixing rates and times were tested. The CO 2 flux was estimated through sequential lectures and the best fit for flux measurements was obtained taking short readings every 3 min, during a total time of 12 min ( R 2 = 0.99). The best mixing rate was attained for 250 mL min −1 , allowing 25 s of mixing previous to CO 2 extraction for an infrared gas analyzer. The deviation of the measured values for dry sand from the reference CO 2 flux (0.097 and 0.071 g m −2 min −1 ) was 5 and 7%. On dry sandy loam soil (SLS) the deviation was 2%. The measured fluxes decreased 73 and 22% with content moisture of 20 and 10% (sand), and 78% with content moisture of 31% (SLS). This work allowed to estimate how much the measured emission rates deviate from the true ones for the specified chamber and sampling conditions.