Nontargeted Identification and Prioritization of Organic Contaminants in Biosolid-Amended Soils across the United States

Abstract

The widespread use of biosolids as an agricultural soil amendment has raised concerns about the release of organic contaminants into the environment. This study identifies biosolids-associated organic contaminants (BOCs) in soils from municipal biosolid-amended plots across the United States. Soil samples were collected from 18 sites in 15 states, representing biosolids applications from the 1980s to the present. Samples were taken at three depths (30, 90, and 180 cm) from plots with no, low, and high application histories. Samples were extracted using QuEChERS and analyzed by liquid chromatography–high-resolution mass spectrometry (LC-HRMS) using a nontargeted analysis (NTA) approach. A total of 111 BOCs were detected across biosolid-amended plots. BOCs were detected most frequently in surface soils (30 cm), with significantly fewer detections at subsurface depths (p < 0.001). Cumulative loading rate and application frequency were significant predictors of the number of BOCs detected (p = 0.003 and p = 0.017, respectively). Quality-adjusted hazard scores for human health, ecological impact, and environmental fate identified 4-nitrophenol (44%), PFBS (41%), and miconazole (38%), among others as the highest-priority BOCs. This NTA-hazard prioritization workflow provides a strategy for identifying compounds warranting further evaluation for potential environmental and human health risks.