Laser Photoacoustic Detection of CO2 in Old Disc Tree-Rings

• Main Authors: Boris Ageev, Yurii Ponomarev, Valeria Sapozhnikova
• Format: Article
• Language: English
• Published: MDPI AG 2010-04-01
• Series: Sensors
• Subjects: laser photoacoustic gas analysis; carbon dioxide; tree-rings; H2O
• Online Access: http://www.mdpi.com/1424-8220/10/4/3305/

A homemade CO2–laser photoacoustic spectrometer has been used for monitoring CO2 in gas samples extracted under vacuum from the wood of old spruce disc tree-rings for a ~60 year series. The experimental results show that (1) the CO2 concentration exhibits annual trends correlated with an increase in atmospheric CO2 in a number of cases; (2) at the time when the annual CO2 trend changes from positive to negative, the annual tree-ring stable carbon isotope ratios (δ13C) of CO2 change as well; (3) the disc tree-ring widths are observed to decrease in most cases where the annual CO2 increased; (4) simultaneously with the annual CO2 variation, annual H2O distribution was detected in gas samples of the wood tree-rings of one spruce disc. The observed patterns of the annual CO2 distribution in the disc tree-rings are assumed to be the evidence of the impact of the atmospheric CO2 increase. In other words, a change in the concentration gradient between the stem and the atmospheric CO2 may lead to a gradual CO2 accumulation in the stem because of a decrease in the diffusion rate and to a change in the tree parameters.