Plant− Soil Distribution of Potentially Toxic Elements in Response to Elevated Atmospheric CO2

The distribution of contaminant elements within ecosystems is an environmental concern because of these elements’ potential toxicity to animals and plants and their ability to hinder microbial ecosystem services. As with nutrients, contaminants are cycled within and through ecosystems. Elevated atmospheric CO₂ generally increases plant productivity and alters nutrient element cycling, but whether CO₂ causes similar effects on the cycling of contaminant elements is unknown. Here we show that 11 years of experimental CO₂ enrichment in a sandy soil with low organic matter content causes plants to accumulate contaminants in plant biomass, with declines in the extractable contaminant element pools in surface soils. These results indicate that CO₂ alters the distribution of contaminant elements in ecosystems, with plant element accumulation and declining soil availability both likely explained by the CO₂ stimulation of plant biomass. Our results highlight the interdependence of element cycles and the importance of taking a broad view of the periodic table when the effects of global environmental change on ecosystem biogeochemistry are considered.