Location: Food Animal Metabolism Research
Project Number: 3060-32420-003-017-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 15, 2023
End Date: Apr 30, 2027
Objective:
Four objectives are envisioned:
1) Screen a large suite of biochars (50-60 biochars made from various feedstocks under varying pyrolysis conditions) for sorption of PFAS compounds from solution (under laboratory conditions);
2. Utilize those biochars that sorb the maximum quantity of PFAS from solution, and attempt to desorb PFAS from the biochar matrix (again, in solution under laboratory conditions). Understand if the biochar-PFAS complex is potentially bioaccessible;
3. Utilize those ‘best’ biochars (max PFAS sorption, min PFAS desorption) in a greenhouse study with one to two PFAS-containing soils. Identify which biochars a) maintain or improve soil health, b) reduce PFAS leaching, b) reduce PFAS uptake in plants, and d) reduce potential soil ingestion risk to animals; and
4. Use the ‘best’ biochar (from the greenhouse study) in a field setting, focusing on PFAS sorption, reduction in plant uptake, and maintenance/improvements in soil health.
Approach:
1) Obtain Biochars:
Obtain a suite (50-60) of biochars from various feedstocks and pyrolysis conditions. Biochars will be collected from PFAS contaminated sites; alternatively feedstocks from locally contaminated sites will be used to create biochars.
2. PFAS-Biochar Sorption:
The suite of biochars will be screened for PFAS sorption under laboratory conditions. Biochars (~5 g) will be introduced into a solution (100 mL) containing known quantities of PFASs: PFOA, PFOS, PFNA, PFHxS, PFBS and HFPO-DA (GenX). Biochar mixtures will be stirred for 48h, followed by separation from the biochar via filtration. Solutions will be analyzed for PFAS using validated methods. Biochars will be rinsed, air-dried, and stored. Biochars that sorbed the maximum amount of PFAS will be used in step 3.
3. PFAS-Biochar Desorption
Selected, air-dried biochars (~4 g) will be placed in CaCl2 solution (80 mL) and stirred for 48h, followed by filtration. Solutions will be analyzed for desorbed PFAS. Biochars that desorbed the least amount of PFAS will be a) analyzed for PFAS desorption via an in-vitro assay to determine potential animal risk post-ingestion, and b) carried forward to step 4.
4. Greenhouse Trial
Selected biochars from step 3 (no more than 3-6 biochars total) will be added to PFAS contaminated soil (e.g., from Maine; collected by NRCS).
a. Biochars will be thoroughly mixed into soils at 4 rates (0, 0.5, 1.0, 1.5% wt:wt) utilizing 4-5 replicates per rate.
b. A cool season grass mix (identified as CP1) will be raised in each pot.
c. Water holding capacity at field capacity of each biochar-soil treatment will be determined prior to experimental launch. Based on field capacity determination, all experimental pots will be held at approximately 70% field capacity via manual irrigation several times per week over the study duration.
d. Soils will be leached with ~ 1.1 pore volumes of water at 1, 2, 3, and 4 months; selected leachates will be initially analyzed for PFAS, and if need be, additional leachates will be analyzed to fill data gaps.
e. Plants will be raised for 4-5 months, followed by manual harvesting of all above-ground plant biomass. Plants will be analyzed for PFAS.
f. Soils will be analyzed using an in-vitro assay to determine potential animal risk.
5. Field Trial: Based on greenhouse findings, a 2-year field trial in a PFAS contaminated soil (in Maine) will be performed.
a. Biochar will be incorporated into the top 6” of soil and planted with CP1; a control (no biochar) will also be utilized.
b. A minimum of 6 replicates of 3 x 3 m plots.
c. Pre- and post-study soils will be collected to determine soil health (via SMAF), PFAS concentrations, and used for in-vitro analyses to determine PFAS risk to animals post-ingestion.
d. Post-study, 0.5 sq. meter quadrats will be utilized to collect above ground biomass and to determine PFAS concentrations in plants.
