Leaf radiocarbon data from two plant species in Saint Paul, Minnesota, USA 2020

Over half of Earth’s human population lives in urban areas, where pollution from carbon-based fossil fuel combustion threatens air quality and public health, and contributes significantly to the rapid increase of greenhouse gases. The isotopic composition of plant tissues can be used as a tool to estimate local variation in fossil fuel-derived carbon dioxide and thus contributions of fossil fuel combustion to the local atmosphere in urban anthromes. We present a case study that examines this variation in leaf modern radiocarbon content against a backdrop of historic discriminatory policies (here, ‘redlining’), within Saint Paul, Minnesota, USA. Radiocarbon values from leaves suggest varied distribution of atmospheric fossil fuel derived carbon emissions across Saint Paul greenspaces, with evidence of higher exposure near areas of high-volume traffic. Similar studies rarely measure plant material from both perennial and annual plants: here we report carbon values from leaves from a deciduous tree and an annual forb to compare function differences in carbon age. Isotopic carbon signatures in plant material capture evidence of emissions that may reveal unequal pollution exposure. 

Leaf samples were collected in August 2020 in Saint Paul, Minnesota, USA. Radiocarbon samples were run at UC-Irvine Keck AMS in Fall 2020.

Accompanying article Heskel, Hrycyna et al. (2024) is published in Plants, People, Planet (specific information on the paper to be shared when available).

Plant Genus Fraxinus; Taraxacum 

HOLC: Identifying letter and color according to the sampling location based on historical Home Owner's Loan Corporation maps.

Site: Code for public park location. More specific details available in article. 

Latitude: Sampling latitude 

Longitude: Sampling longitude

Distance to major roadway (m): Distance from the sampling site to either a highway or major road (4 lanes or greater) in Saint Paul, in meters

Δ14C value: Measured value of leaf Δ14C

Δ14C SD: Measured standard deviation of leaf Δ14C

CO2-FF: amount of CO2 that is derived from fossil fuel combustion for each leaf sample. Details on this calculation is in the article.