Time series of atmospheric Δ14CO2 recorded in tree rings from Northwest China (1957–2015)

• Published in: Chemosphere (Oxford) 2021-06, Vol.272, p.129921, Article 129921
• Main Authors: Xiong, Xiaohu, Zhou, Weijian, Hou, Xiaolin, Cheng, Peng, Du, Hua, Zhao, Xue, Wu, Shugang, Hou, Yaoyao, Lu, Xuefeng, Fu, Yunchong
• Format: Article
• Language: English
• Subjects: Bomb curve; Fossil CO2; Northwest China; Tree ring; Δ14CO2 records
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2021.129921

Radiocarbon (14C) is a unique and important tool for understanding carbon cycle in the nature, and its use can be significantly enhanced where reliable historical atmospheric Δ14CO2 records can be established. In China, continuous atmospheric Δ14CO2 records since the 1950s are scarce, a period when dramatic variations of Δ14CO2 occurred caused by intensive human activities. In this research, Δ14C of Qinghai spruce tree rings collected from Huangzhong (HZ) (36.27°N, 101.67°E, 2982 m amsl) were measured by Accelerator Mass Spectrometry, and a Δ14CO2 time series from 1957 to 2015 was reconstructed. The results show that HZ Δ14C was generally higher than the contemporaneous average level in the mid-high latitudes of the Northern Hemisphere. The peak value of HZ Δ14C occurred in 1964 (as bomb peak) was higher than that of other tree ring records in East Asia at a similar latitude, likely due to the impact of the atmosphere nuclear tests at Semipalatinsk (Kazakhstan). The record shows no obvious disturbance of Lop Nor nuclear weapons tests (in Northwest China) during 1964–1980, except for 1971. A local Suess effect began to appear since 2001, and the estimated atmospheric fossil fuel-derived CO2 (CO2ff) concentration increased from 3.5 ppm to 8.8 ppm from 2006 to 2015. This is associated with the implementation of the “Western Development” strategy in China. HZ Δ14C records document background Δ14C data, useful for regional carbon cycle research and atmospheric CO2ff quantification in the region. These data also provide baseline values for assessment environmental safety connected with nuclear power plants in China. Temporal variation of Δ14C in tree rings of Huangzhong (HZ) in Northwest China in 1957–2015 compared with average Δ14CO2 at mid-high latitude (NH-2 and NH-1) in the North Hemisphere. [Display omitted] •A Δ14CO2 record during 1957–2015 in northwest China was first reconstructed.•This Δ14CO2 record was generally higher than the other records at similar latitude.•The Δ14CO2 records can be used as background data for carbon cycle study.•These data would help assess the environment safety connected with nuclear energy.