Using radiocarbon of plants to track inequity in urban environments

Societal Impact Statement Over half of Earth's human population lives in urban areas where pollution from fossil fuel combustion threatens urban air quality and public health. The isotopic composition of plant tissues can be used as a tool to estimate local variation in the amount of fossil fuel–derived carbon dioxide. We present a case study that examines this variation against the backdrop of historic discriminatory policies in Saint Paul, Minnesota, USA. Data suggest higher loads of atmospheric fossil carbon in neighborhood greenspaces that are situated closer to large roads, which often correspond with historical policies. Evidence of unequal fossil fuel combustion, and potentially pollution load, may precipitate changes in urban management or pollution mitigation strategies.