Modeling PFAS Bioaccumulation in Different Crop Compartments Based on Varied Biosolid Application Frequencies

Abstract

Per-/Poly- fluoroalkyl substances (PFAS) are a class of contaminants that are widely used in everyday applications as a result of their desirable properties which in turn makes them chemicals which are highly persistent in the environment [1]. As a result, it is essential to understand how PFAS will behave in the environment and the potential risks they pose to the environment, humans, and animals. This thesis focused on studying the bioaccumulation of PFAS in corn and carrot crops as a result of biosolid application to agricultural land. This exposure pathway is studied since the bioaccumulation of PFAS in edible crop compartments would directly expose consumers to these chemicals. To understand how the concentration of PFAS in biosolids impacts the concentration of PFAS in crops, three different biosolid application scenarios were studied, for two different crop types, four different PFAS, and at different growing seasons in a ten year period. The transport of PFAS from biosolids to the soil and into the crop is studied through the mechanistic model, HYDRUS 1D, and experimentally derived bioaccumulation factors. This study found that PFOS had the greatest concentration level within all crop compartments while PFOA, PFBS, and PFPeA had smaller levels. Out of all of the PFAS, PFBS had the lowest concentration in edible crop compartments and yielded the largest allowable mass consumption for corn and carrots. It was also determined that as the frequency of biosolid application decreased, the maximum allowable consumable mass increased. So, in the case of PFPeA, PFOA, and PFOS, changes should be made to the frequency of biosolid application or initial concentration in the soil profile to minimize the amount of PFAS accumulation in edible crop compartments.