Uptake of per- and polyfluorinated alkyl substances by dry farmed oats following the agricultural application of biosolids and compost

Abstract

A significant portion of municipal biosolids is land applied, often to support crop production. Although per- and polyfluoroalkyl substances (PFAS) are widely detected in biosolids, their fate in agricultural systems is not yet fully understood, especially at the field-scale. This study evaluated the uptake of 33 PFAS compounds with chain lengths of C3–C18 over one growing season in dry farmed oats grown in soils on two fields with a long history of receiving biosolids amendments. No PFAS compounds were detected in the crops grown in the two biosolids-amended fields, nor in oats grown on three subplots of a nearby USDA Certified Organic field receiving no amendment, compost, and a combination of compost and lime. Nine PFAS compounds were detected in biosolids samples at two sites with ∑_PFAS equal to 95.4 μg kg⁻¹ and 8.9 μg kg⁻¹, dominated mainly by perfluorooctane sulfonate (PFOS), perfluorohexanoic acid (PFHxA), and perfluorooctanoic acid (PFOA). Soil residuals before application and at the time of harvest were mainly defined by concentrations of PFOS, followed by other perfluoroalkyl acids and were not significantly different before and after the years' growing season. No residues were detected in dry-farmed oats grown on biosolids- or compost-amended fields in this study, suggesting that the likelihood of the PFAS compounds studied here accumulating in similar crops grown under similar conditions is minimal.