Anthropogenic CO₂in the Dakar (Senegal) Urban Area Deduced from¹⁴C Concentration in Tree Leaves

Abstract

Radiocarbon (14C) in atmospheric CO2 for the Dakar (Senegal) urban area was measured using tree leaves collected by botanists from 1900 to 2003. The aim of our study was to compare the local Suess effect in Dakar to the global one during the 20th century. The ∆14C of atmospheric CO2 in this region decreased from 1900 to 1958 during the pre-bomb era (–2±5‰ to –22±4‰). From 1958 to 1964, nuclear bomb tests injected a large amount of artificial 14C into the atmosphere, reflected in the rise of ∆14C values. In the Dakar region, the atmospheric ∆14C reached 773±8‰ in 1964, but subsequently decreased to 80±5‰ by 2003, which is consistent with the global exponential decreasing trend. The ∆14C record presented here remains slightly lower than the global record. This result is attributed to the input of anthropogenic fossil carbon into the atmosphere. The amount of carbon input can be evaluated by comparing urban areas to those of clean air sites. The calculation of anthropogenic fossil carbon is deduced from a simple mathematical model.

Description of a global marine particulate organic carbon-13 isotope data set

“…It helps to diagnose carbon pathways from the atmosphere to the deep ocean including the biological carbon pump (e.g., Jasper and Hayes, 1990;Popp et al, 1989;Freeman and Hayes, 1992) and assists reconstruction of oceanic carbon cycling and even plankton cell size and community structure (e.g., Tuerena et al, 2019;Lorrain et al, 2020). For example, anthropogenic carbon emissions have a distinctly low δ 13 C content, making δ 13 C a useful property for tracing anthropogenic carbon throughout the Earth system (Eide et al, 2017;Levin et al, 1989;Ndeye et al, 2017). Atmospheric δ 13 C CO 2 has decreased from −6.5 ‰ in preindustrial times to −8.4 ‰ presently (Rubino et al, 2013).…”

Fossil Carbon Load in Urban Vegetation for Debrecen, Hungary

“…These studies generally used deciduous plant leaves, specifically Ginkgo biloba L., Zea mays L., Agropyron repens (L.) Gould, Ficus sp., Setaria viridis (L.) P. Beauv. samples and past studies have shown a low but detectable 14 C dilution close to densely populated areas (Hsueh et al 2007;Riley et al 2008;Zhou et al 2014;Park et al 2015;Ndeye et al 2017).…”

Characteristics of Pine Needles Exposed to Multi-Source Pollution in Silesia: Radiocarbon Concentration in Pine Needles and Elemental Analysis of the Needles’ Surface Deposits

“…Increasing anthropogenic carbon dioxide emissions into the atmosphere due to the combustion of large amounts of fossil fuel combustion has changed the local and global carbon cycle. The impact of these carbon dioxide emissions on the isotopic concertation in trees (tree rings and foliage) is evident (Suess 1955;Molnar et al 2007;Hua et al 2013;Pazdur et al 2013;Baydoun et al 2015;Ndeye et al 2017). The physiological processes of trees, such as their photosynthesis rate and stomatal conductance, can be affected not only by carbon dioxide, but also by other air contaminants, gases, and dust associated with human activities, such as industrial processes, road transport, and low and high-stack emissions (Staszewski et al 1994).…”