The accumulation of metals, PAHs and alkyl PAHs in the roots of Echinacea purpurea

• Published in: PloS one 2018-12, Vol.13 (12), p.e0208325
• Main Authors: Pretorius, Travers R, Charest, Christiane, Kimpe, Linda E, Blais, Jules M
• Format: Article
• Language: English
• Subjects: Accumulation; Alkyl groups; Arbuscular mycorrhizas; Aromatic hydrocarbons; Bioaccumulation; Biology; Biology and Life Sciences; Bioremediation; Chemical plants; Chemical properties; Contaminants; Contamination; Depletion; Earth Sciences; Echinacea; Echinacea - metabolism; Echinacea purpurea; Ecology and Environmental Sciences; Engineering and Technology; Environmental management; Environmental Monitoring; Experiments; Fungi; Greenhouse effect; Hydrophobicity; Inoculation; Metal concentrations; Metals; Minerals; Mycorrhizae - metabolism; Physical Sciences; Physiological aspects; Plant extracts; Plant growth; Plant Roots - metabolism; Plants (botany); Pollutants; Polycyclic aromatic hydrocarbons; Polycyclic Aromatic Hydrocarbons - metabolism; Residual soils; Roots; Sediment pollution; Seeds; Soil conditions; Soil contamination; Soil pollution; Soils
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0208325

We examined the accumulation of polycyclic aromatic hydrocarbons (PAHs), alkyl PAHs, and toxic metals in soils by the roots of Echinacea purpurea (L.) Moench, in a 20-week greenhouse study and a 2-year field study. In the greenhouse study, inoculation by arbuscular mycorrhizal fungus (AMF), Rhizoglomus intraradices (N.C. Schenck & G.S. Sm.). increased the first order accumulation rates (k1) for PAHs by 10-fold, though had no effect on the bioaccumulation rates of toxic metals. In the greenhouse study, PAHs concentrations in soil increased over time with AMF inoculation, suggesting AMF promote 'solvent depletion' in soils by enhancing absorption of minerals and carbon by roots, concentrating the more hydrophobic PAHs in the residual soil. Under field conditions, contaminant concentrations in soils remained unchanged over the 2-year duration of the study. Despite this, all contaminants in E. purpurea roots increased significantly, as a result of a long term extraction of contaminants by plants from soil and a reduction in soil volume as a result of plant growth. First order accumulation rates by roots were inversely correlated to log Kow for the PAHs and alkyl PAHs, indicating that accumulation is inversely related to the compound's hydrophobicity. This study is the first to our knowledge to assess the accumulation of alkyl PAHs by roots, with implications for soil bioremediation by plants because alkyl PAHs are a major source of petrogenic contamination in soils.