Abstract
The concentrations of tropospheric CO2 and O3 have been rising due to human activities. These rising concentrations may have strong impacts on soil functions as changes in plant physiology may lead to altered plant-soil interactions. Here, the effects of eCO2 and eO3 on the removal of polycyclic aromatic hydrocarbon (PAH) pollutants in grassland soil were studied. Both elevated CO2 and O3 concentrations decreased PAH removal with lowest removal rates at elevated CO2 and elevated O3 concentrations. This effect was linked to a shift in soil microbial community structure by structural equation modeling. Elevated CO2 and O3 concentrations reduced the abundance of gram-positive bacteria, which were tightly linked to soil enzyme production and PAH degradation. Although plant diversity did not buffer CO2 and O3 effects, certain soil microbial communities and functions were affected by plant communities, indicating the potential for longer-term phytoremediation approaches. Results of this study show that elevated CO2 and O3 concentrations may compromise the ability of soils to degrade organic pollutants. On the other hand, the present study also indicates that the targeted assembly of plant communities may be a promising tool to shape soil microbial communities for the degradation of organic pollutants in a changing world.
Highlights
Global industrialization has led to an increase of tropospheric carbon dioxide (CO2) concentration from approximately 280 ppm in pre-industrial times to approximately 380 ppm nowadays, and it is expected to continue increasing in the future[1,2]
Since soil microbial communities and their activity are profoundly affected by plant community composition[15,16,17,18], polycyclic aromatic hydrocarbon (PAH) removal may be influenced by changes in plant community composition and diversity
CO2 × O3 had a significant interactive effect on total PAH residuals as remaining PAHs were lowest at aCO2 and aO3, but substantially increased by eCO2 and eO3 and highest at both eCO2 and eO3 (+43% in comparison to ambient conditions)
Summary
Global industrialization has led to an increase of tropospheric carbon dioxide (CO2) concentration from approximately 280 ppm in pre-industrial times to approximately 380 ppm nowadays, and it is expected to continue increasing in the future[1,2]. Phytoremediation of PAHs from soils was conducted by a single plant species[11,12] and the mechanisms linking plants and PAH removal are still elusive It remains unclear whether and how global environmental change agents will affect phytoremediation of PAHs from soils. Soil microorganisms are important mediators of global change effects as several soil bacteria and fungi produce enzymes that break down PAHs, contributing to soil remediation. This effect is especially pronounced in microbial communities associated with plant roots[13,14], where microbes are directly stimulated by the presence of Blumenbach Institute of Zoology and Anthropology, University of Göttingen, Berliner Str. 28, 37073, Göttingen, www.nature.com/scientificreports/. The functional composition of plant communities can drive belowground communities and processes[22,23], e.g. through specific plant traits affecting nutrient availability[24,25,26]
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