The national research project being led by University of Arizona professor Ian Pepper looking at the fate and transport of PFAS in land applied biosolids project has made considerable progress. The project team issued a 7-page report in July. It says the project has collected what to date is believed to be the largest US data set on “incidence and distribution of biosolids derived PFAS”.

The National Collaborative PFAS study includes 23 sites with a documented history of biosolids use spread across 17 states. One site was eliminated from the research because the biosolids used had been industrially-impacted. The purpose of this study is to look at what happens when non-contaminated biosolids are used. At these sites where the past application rate of biosolids is known, the team sampled the soil at 1, 3 and 6 foot intervals. They also sampled groundwater when possible and plan to get groundwater samples at the sites in the future. A total of 27 soil samples are taken at each site for 25 “representative” PFAS compounds.

Sampling and analysis has been completed at 14 of the 23 sites and the researchers present their findings to date in the July report. So far, they haven’t found anything alarming at these sites with past histories of land application of biosolids. They noted the highest incidence was for PFOS found in the soils studied. They observed rapid attenuation of PFAS concentrations from 3 to 6 feet soil depths and noted a greater risk of leaching for the short-chain PFAS compounds studied. Analyses continue.

The researchers are using this large dataset to model PFAS leaching from biosolids to groundwater. They have developed a customized model and hope to test the predicted concentrations in groundwater against the actual concentrations at the sites whenever possible.

Phase 2 of this project – which will require additional funding – will build on the work in Phase 1. The researchers are hoping to grow crops on these plots -- that they now have lots of data on -- to study the potential for crop uptake of PFAS in the biosolids-amended soils.

If you would like to pledge a financial commitment to Phase 2, please email Dr. Ian Pepper at ipepper@ag.arizona.edu.