Perfluorooctanoic Acid Transport in Soil and Absorption and Distribution in Alfalfa (Medicago sativa)

Abstract

Perfluorooctanoic acid (PFOA) is used as a surfactant in consumer and industrial products and is frequently found in biosolids from wastewater treatment plants. When present in biosolids applied to croplands, PFOA can contaminate feed and fodder used by livestock, but the extent of PFOA transfer from soil to plants is not well characterized. A single dose of radiocarbon (14C)-tagged PFOA was applied to unplanted soil or soil containing growing alfalfa. PFOA transport through unplanted soil and uptake by alfalfa was monitored over a 10-week study period. Radiocarbon was initially measured in roots, stems, and leaves 7 days after [14C]-PFOA application to soil. PFOA accumulation was greatest in leaves during the 10-week sampling. By week 10, PFOA migration through unplanted soil had reached a depth of 22.8 ± 2.5 cm. In contrast, PFOA migrated to 7.5 ± 2.5 cm in soil containing alfalfa plants. The greatest predictor of PFOA concentration in alfalfa leaves was PFOA concentration in the top 5 cm of soil; PFOA concentrations at lower depths were not correlated with alfalfa PFOA concentrations. PFOA transport through soil may be slowed by the presence of forage; however, PFOA accumulation in edible portions of forage plants may increase food animal exposure to PFOA residues.