Grantee Research Project Results
2021 Progress Report: Evaluating PFAS Occurrence and Fate in Rural Water Supplies and Agricultural Operations to Inform Management Strategies
EPA Grant Number: R840082Title: Evaluating PFAS Occurrence and Fate in Rural Water Supplies and Agricultural Operations to Inform Management Strategies
Investigators: Lee, Linda S. , Pennell, Kurt , Preisendanz, Heather
Institution: Purdue University
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2020 through August 31, 2023 (Extended to August 31, 2025)
Project Period Covered by this Report: September 1, 2020 through August 31,2021
Project Amount: $1,609,344
RFA: National Priorities: Research on PFAS Impacts in Rural Communities and Agricultural Operations (2020) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management
Objective:
Our overall goal, which includes 6 objectives, is to address key data gaps in our understanding of PFAS occurrence and fate in the rural landscape and agricultural operations and their impacts on rural water supplies and agricultural products using a combination of field, laboratory and modeling activities to evaluate the following objectives.
Progress Summary:
In year 1, we made varying degrees of progress on all objectives. For Obj. 1 (to evaluate the contribution of effluent and land-applied biosolids to PFAS in rural water sources), we have collected and analyzed a subset of biosolids and rural well water samples (Indiana) to date as well as influent and effluent from the Penn State water resource recovery facility (WRRF) for Oct, Dec 2020 and Feb, April, June, and Aug 2021. The latter are being combined with data collected the year prior to the start of this project to evaluate PFAS occurrence trends. Biosolids collected in IN ranged in total PFAS (54 analyzed) from 26 to 200 µg/kg dry weight (dw) basis. Differences in source contributions, population served, and treatment processes are being evaluated with regards to PFAS totals. Twelve sets of rural well water samples have been in IN to date and for the 8 sets analyzed, total PFAS ranged from 2 to 22 ng/L. Additional IN wells have been identified for sampling where biosolids land-application is high. Penn State already has 74 volunteers from their private rural well-owner network for well water sampling. For Obj. 2 (to evaluate PFAS fate, transport, and crop uptake in a site-specific field study from spray-irrigation with WRRF effluent from Obj. 1), well-water sampling and crop silage samples were collected and fescue (hay) at the Penn State wastewater spray-irrigation ‘Living Filter’ site. Overall, total PFAS concentrations across the Living Filter generally increased in the direction of with groundwater flow concentrations, but PFOS+PFOA remained below 70 ng/L for all samples collected from the monitoring wells. The highest PFAS concentration in the corn silage was PFBA (1.5 µg/kg dw). Spring and Fall 2020 fescue cuttings had total PFAS concentrations ranging from 13.4-16.6 µg/kg dw and 4.31-7.52 µg/kg dw, respectively. Based on the feed rations for non-research dairy cattle raised at Penn State and PFAS concentrations obtained from 2019 and 2020 harvests, the total annual PFAS consumption was estimated to be 21-36 mg/animal/year, with negligible differences between irrigated and non-irrigated corn silage. In all cases, PFBA contributed to >60% of the total PFAS consumption. PFAS present in the crop samples may be from uptake and/or direct spray-irrigation. Dairy feed rations were used to estimate PFAS consumed by Penn State’s non-research dairy cattle, which consume fescue and corn grown at the spray-irrigation site. For Obj. 3 (to evaluate PFAS fate, transport, and crop uptake in a site-specific study from land-applied biosolids and potential mitigation strategies), we have done some background groundwater samples and one set of soil cores from the VA HRSD Progress agricultural farm site in preparation for the field study that will embark in March/April 2022. We have also conducted PFAS analysis associated with an artificially constructed land-reclamation field study for which biosolids from three sources were used as soil amendments compared to synthetic fertilizers. Analysis is not complete, but in general, PFAS concentrations in the lysimeters increase with higher application rates and as a function of antecedent conditions, rainfall intensity, and rainfall frequency. For Obj. 4 (to evaluate the PFAS precursor occurrence in land-applied biosolids and their relative persistence in lab-based studies), we found that typically 97% of the quantifiable PFAS are precursors (PFAS leading to perfluoroalkyl acids, PFAAs) in biosolids with the largest contributors being the phosphate esters. Efforts to identify larger side-chain polymers are ongoing. For Obj. 5 (to evaluate PFAS interfacial adsorption in the unsaturated zone), unsaturated (~80% moisture) columns packed with a reference Ottawa sand or Appling soil were performed at Brown University. PFOS had the highest interfacial sorption (i.e., solid-water, air-water adsorption) and greatest tailing of the breakthrough (consistent with a nonlinear adsorption-desorption) compared to other PFAAs. Earlier breakthrough and less tailing of PFNA compared to PFOS in both columns reflects the importance of the polar functional group in the adsorption process. For Obj. 6 (to refine and validate mathematical models to predict PFAS leaching to water resources based on lab and field results). Two field-scale contaminant fate and transport models (PRZM5 and Hydrus 1D) were modified to incorporate nonlinear interfacial adsorption at Brown University. The modified models were applied to representative literature data to evaluate their performance. Based on these results, the modified version of Hydrus 1D was selected for subsequent testing using field data from the Living Filters site at Penn State University.
Future Activities:
Penn State WRRF sample collection will continue throughout the remainder of the project period. Biosolids (IN) and well water sample collection and analysis (IN and PA) will continue (Obj. 1). Sampling and analysis of the monitoring wells and crops at the Penn State wastewater spray-irrigation field site will continue throughout the remainder of the project period (Obj. 2). Sampling and analysis of the VA HRSD Progress agricultural farm site will be ongoing for the remainder of the project. Analysis of the artificially constructed land reclamation site will be completed in Year 2. Additional unsaturated columns will be conducted using Appling soil and field soil from PFAS-impacted biosolids application field site (Obj. 3) and an effluent water application field site (Obj. 2) at two different water saturations of 25 and 30% (Obj. 5). PFAS fate and transport in unsaturated soils using the modified version of Hydrus 1D will continue using additional PFAS soil profile data obtained from Obj. 5 including a sensitivity analysis to investigate effects of environmental conditions along with validating and improving modified Hydrus 1D using PFAS soil distribution profiles and lysimeter data collected under Objs. 2 and 3 (Obj. 6) scale.
Journal Articles:
No journal articles submitted with this report: View all 19 publications for this projectSupplemental Keywords:
biosolids, effluent irrigation, crop uptake, transport, biotransformation, interfacial adsorptionProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.