Laser photoacoustic detection of CO2 in old disc tree-rings.
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.
Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Sciences, Academician Zuev Square, 1. Tomsk, 634055, Russia. ageev@asd.iao.ru
Boris
B
Ageev
Yurii
Y
Ponomarev
Valeria
V
Sapozhnikova
D000162:Acoustics / Q000295:instrumentation; D001272:Atmosphere; D002245:Carbon Dioxide / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis; D007834:Lasers; D028222:Picea / Q000737:chemistry*; D014934:Wood / Q000737:chemistry*
D002247:Carbon Isotopes; D002245:Carbon Dioxide