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Long‐term record of atmospheric CO 2 and stable isotopic ratios at Waliguan Observatory: Background features and possible drivers, 1991–2002
Author(s) -
Zhou Lingxi,
Conway Thomas J.,
White James W. C.,
Mukai Hitoshi,
Zhang Xiaochun,
Wen Yupu,
Li Jinlon,
MacClune Kenneth
Publication year - 2005
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2004gb002430
Subject(s) - plateau (mathematics) , environmental science , biosphere , southern hemisphere , biogeochemical cycle , carbon cycle , northern hemisphere , atmospheric sciences , climatology , δ13c , isotopic ratio , climate change , observatory , stable isotope ratio , geology , isotope , environmental chemistry , chemistry , oceanography , mathematical analysis , ecology , physics , mathematics , ecosystem , astrophysics , biology , quantum mechanics
This paper describes background characteristics of atmospheric CO 2 and stable isotopic ratios (δ 13 C and δ 18 O) as well as their possible drivers at Waliguan Baseline Observatory (WLG) (36°17′N, 100°54′E, 3816 m above sea level) in the inland plateau of western China. The study is based on observational CO 2 data (NOAA Climate Monitoring and Diagnostics Laboratory discrete and WLG continuous measurements) obtained at WLG for the period from May 1991 to December 2002. Over this period the change in monthly means is ∼+16 ppm for CO 2 , ∼−0.2‰ for δ 13 C, and ∼−0.5‰ for δ 18 O. The overall increase of CO 2 and subsequent decline of δ 13 C, with a Δδ 13 C/ΔCO 2 ratio (−0.011 ± 0.105) ‰ ppm −1 at WLG, reflect the persistent worldwide influence of fossil fuel emissions. The negative secular trend of δ 18 O at WLG is probably due to vigorous 18 O exchange with soils in the Northern Hemisphere (NH) and conversion from C 3 to C 4 plants via land use change. The CO 2 , δ 13 C, and δ 18 O mean annual cycles with peak‐to‐peak annual amplitudes of ∼10.5 ppm, ∼0.499 ‰, and ∼0.819‰, respectively, at WLG show typical middle‐to‐high NH continental features that correspond to the seasonal cycle of the terrestrial biosphere. The significant CO 2 and δ 13 C interannual variability at WLG is very likely caused by worldwide climate anomalies and associated regional fluctuation in biospheric CO 2 uptake in the Asian inland plateau as well as long‐range air mass transport. The results of this study help to provide a basic understanding of the individual sources and sinks of carbon in this area and help us to better address the role of the Asian inland terrestrial biosphere in the global carbon cycle.