Jing Li†,‡, Boji Lin†, Nannan Wei†,∥, Weimin Wang*,§, Jun Li†,‡, Wenbiao Feng†, Zhineng Cheng†,‡, Sanyuan Zhu†,‡, Tao Zhang⊥, Duohong Chen⊥, and Gan Zhang*,†,‡
† State Key Laboratory of Advanced Environmental Technology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
‡ Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou 510640, China
§ Shenzhen Ecological and Environmental Monitoring Center of Guangdong Province, Shenzhen 518049, China
∥ School of Nuclear Science and Technology, University of South China, Hengyang 421001, China
⊥ Environmental Key Laboratory of Regional Air Quality Monitoring, Ministry of Ecology and Environment, Guangdong Ecological and Environmental Monitoring Center, Guangzhou 510308, China
Contact to: Jing Li (lijing@gig.ac.cn).
Top-down quantification of fossil fuel-derived CO2(CO2ff) using radiocarbon (14C) relies on the Suess effect, whereby14C-free fossil emissions dilute atmospheric 14CO2. However, 14C releases from nuclear power plants (NPPs) enrich ambient 14CO2, offsetting fossil dilution and biasing CO2ff low. Pressurized water reactors (PWRs), dominant in China, emit most 14C as 14CH4, but the smaller14CO2 fraction may still affect nearby air. We investigatedthe influence ofPWR-derived 14CO2 from the Daya Bay and Lingao NPPs (Shenzhen, China) using grass samples collected in January 2025,representing 2024 growing-season carbon,together with a previously published 2022 vegetation Δ14C dataset for comparison and joint spatial analysis.Results showdetectable14CO2 enrichment, with positive Δ14C values up to +3.2‰, confined to the northern near-field(<5 km downwind).Outside this zone, Δ14C remained negative overall (−13.1‰ to −42.1‰), with no consistent 14CO2 enrichment either at more distant sites or south of the NPPs. A first-order CO2ff-equivalent calculation indicates that this enrichment has an offsetting capacity of 8.3–8.8 ppm CO2ff,exceeding the median apparent CO2ffsignal at sites beyond ~5 km. These findings demonstrate that PWR-derived 14CO2 can cause localized, directional interference in Δ14C-based CO2ff reconstructions, highlight the need to integrate nuclear 14C footprints into top-down CO2ff frameworks.
Nuclear power plants (NPPs), Pressurized water reactors (PWRs), Radiocarbon, Fossil fuel, Carbondioxide, Carbon emission, Radiocarbon emissions
